CPJNSMTPConnection v3.47 A set of C++ classes to support the SMTP protocol

Welcome to CPJNSMTPConnection, a set of C++ classes to support the SMTP protocol. SMTP for those not familiar with all the internet protocols is the protocol used to send internet email.

Also included with the SMTP classes in the download is a class called "CPJNMD5Hash" which provides for calculation of Cryptographic hashes and HMACs using CryptoAPI: Next Generation (CNG) as well as a class called "CNTLMClientAuth" which provides a reusable client side implementation for NTLM authentication.

Important!: Please note that I have been informed that CPJNSMTPConnection is being used to develop and send unsolicited bulk mail. This was not the intention of the code and the author explicitly forbids use of the code for any software of this kind.

References

• For information about SMTP (Simple Mail Transfer Protocol) you should read RFC 821.
• For information about ESMTP (Extended Simple Mail Transfer Protocol) which obsoletes the original SMTP RFC, you should read RFC 2821.
• RFC 6530, RFC 6531, RFC 6532, and RFC 6533 covers International email.
• RFC 3492 covers Punycode encoding.
• RFC 2045 which defines how MIME attachments are to be handled in a standard SMTP message.
• RFC 822 and RFC 2822 define the ways standard headers are used by SMTP.
• RFC 2110 and RFC 2557 which covers MHTML (aka HTML Email).
• Base64 encoding which is used in various places in SMTP is described in RFC 1113 and RFC 1421. If was eventually referred to as Base64 in RFC 2045
• The details about SMTP authentication are spread across a number of RFCs including RFC 1731, RFC 1869, RFC 2195, RFC 2095, RFC 2245, RFC 2554, RFC 2595, RFC 4616 and RFC 4954.
• The CRAM-MD5 authentication scheme uses a HMAC (Hashed Message Authentication Code) which is described in RFC 2104, while MD5 itself is described in RFC 1321.
• RFC 3461, RFC 3464 , RFC 3798 and RFC 3885 describe DSN's (Delivery Status Notifications).
• The page http://www.activexperts.com/support/activemail/auth/ includes a good description of the AUTH LOGIN, AUTH PLAIN and AUTH CRAM-MD5 authentication schemes which is implemented by CPJNSMTPConnection.
• RFC 3207 define how STARTTLS operates.
• https://developers.google.com/gmail/xoauth2_protocol defines the XOAUTH2 Authentication protocol when used with the Gmail SMTP servers.
• Initial Client Response (SASL-IR) support is described in RFC 4959.

Features

• Simple and clean C++ interface.
• The interface provided is synchronous which provides an easier programming model than using asynchronous sockets.
• The code does not rely on the MFC socket classes. These classes have a number of shortcomings, one of which causes problems when they are used in NT services.
• The code can be used in a console application without any problems.
• A configurable timeout for the connection can be set through the class API.
• The classes are fully Unicode compliant and include Unicode built options in the workspace file.
• As of v1.1, the classes now fully supports sending file attachments.
• Multi CC, BCC & Reply To support is included.
• Support for regular email address formats and multiple email address parsing.
• Full support for MIME and MHTML (aka HTML Email).
• Full support for MIME Charsets.
• Comprehensive sample program included which exercises most of the classes functionality.
• As of v2.61, the classes now fully support sending email over SSL. This means that for instance you can use the Gmail SMTP server "smtp.gmail.com" on port 465. Also note that all of the other features such as authentication are fully supported over SSL. For example to use Gmail you will require some form of authentication such as AUTH PLAIN because it does not operate as an open relay (which would facilitate spam).
• Supports numerous authentication protocols including "AUTH CRAM-MD5", "AUTH LOGIN", "AUTH PLAIN", "AUTH NTLM" & "AUTH XOAUTH2". An "Auto Detection" form of authentication is also supported. In this mode, the authentication protocols supported by the server are detected and the most appropriate protocol is used.
• As of v2.65, the classes include comprehensive support for DSN's (Delivery Status Notifications).

• As of v2.84, the classes include support for MDN's (Message Disposition Notifications)
• As of v2.86, the classes support STARTTLS. This SMTP command allows a standard SMTP plain text connection to be made and assuming the SMTP server supports STARTTLS, the connection can be upgraded to a encrypted connection mid stream. Often SMTP servers only offer STARTTLS via port 25 instead of SSL / TLS on a different port.
• Optionally supports Address header encoding.
• As of v3.29, the classes are only supported on VC 2017 or later.

• As of v3.34, the SMTP classes now compile without MFC.
• As of v3.21, the SMTP classes now support Initial Client Response (SASL-IR).
• As of v3.44, TLS v1.3 is supported. Please note that TLS v1.3 is only available on Windows 11 or Windows Server 2022 or later.

The enclosed zip file contains the CPJNSMTPConnection source code and a simple test program to exercise all of the functions the classes provide.

Copyright

• You are allowed to include the source code in any product (commercial, shareware, freeware or otherwise) when your product is released in binary form.
• You are allowed to modify the source code in any way you want except you cannot modify the copyright details at the top of each module.
• If you want to distribute source code with your application, then you are only allowed to distribute versions released by the author. This is to maintain a single distribution point for the source code.
• Important!!: Please note that I have been informed that CPJNSMTPConnection is being used to develop and send unsolicited bulk mail. This was not the intention of the code and the author explicitly forbids use of the code for any software of this kind without my explicit written consent.

Updates

v3.47 (26 May 2023)

• Updated copyright details.
• Updated modules to indicate that it needs to be compiled using /std:c++17. Thanks to Martin Richter for reporting this issue.

v3.46 (3 December 2022)

• Fixed an issue in CPJNSMTPConnection::ReadSSLResponse when handling SEC_I_RENEGOTIATE return values from GetEncryptedMessage. Thanks to Emir Kapic for reporting this issue.

v3.45 (3 April 2022)

• Updated the code to use C++ uniform initialization for all variable declarations.

v3.44 (3 January 2022)

• Updated copyright details.
• Updated the code and sample app to support TLS v1.3.

v3.43 (27 December 2020)

• Fixed a bug in CPJNMD5Hash::Format where the size of the string was not being set correctly.
• Reimplemented CPJNMD5Hash::Format using CryptBinaryToString.
• Reimplemented CPJNMD5 class using CryptoAPI: Next Generation (CNG) instead of the older MS CryptoAPI
• Renamed CPJNMD5Hash class to CPJNHashResult.
• Renamed CPJNMD5 class to CPJNHash.
• Reworked the CPJNHash to support any hash algorithm supported by CNG.
• Renamed PJNMD5.h module to PJNHash.h.
• Fixed up usage of ATL Unicode <-> ASCII conversion classes.

v3.42 (24 December 2020)

• Changed the logic in CPJNSMTPAddress::GetRegularFormat to insert spaces between the friendly part of the email address and the actual email address. This addresses an issue where SpamAssassin applied a "bad" score to emails generated by this code. Thanks to Mathieu Schroeter for reporting this issue.

v3.41 (13 September 2020)

• CPJNSMTPConnection is now derived publically from SSLWrappers::CSocket. This allows all the public methods of SSLWrappers::CSocket to be accessible from client code. Thanks to Martin Richter for prompting this update.
• Provided a new virtual CPJNSMTPConnection::TraceCommunication method. This method allows you to see all the data sent and received by the class for diagnostic purposes. For example you could provide an option in your app to log the data for customer support issues. Thanks to Martin Richter for providing this update.
• Improved the error handling in CPJNSMTPAddress::PunyCode to handle errors reported by the underlying Win32 API of IdnToAscii which the code uses to do PunyCode encoding of email addresses to support International email and internationalized email addresses. The issue is that the code uses an "IDN_EMAIL_ADDRESS" flag to this IdnToAscii API and this flag is only supported on versions of Windows starting with Windows 8. On earlier versions of Windows such as Windows 7 and Windows 2008 R2, this API fails when you use the IDN_EMAIL_ADDRESS flag. The code now handles this error by throwing an exception rather than ignoring the return value from the API. Previously when the code ignored the return value, it would then crash when it tried to dereference a zero length string. If you must run this code on now unsupported versions of Windows, then please make sure you disable Punycode encoding using the new functions described in the next release note below. Thanks to Darron Redman and Martin Richter for reporting this issue.
• Added a new boolean configuration value to the CPJNSMTPConnection class to determine if punycode encoding should be used. These new methods are SetUsePunyCode and GetUsePunyCode. As described in the previous release note this is necessary to support the code running without errors on versions of Windows earlier than Windows 8. I have added a checkbox to the sample application to demonstrate using this. By using SetUsePunyCode(false), the code will not of course be able to support internationalized email addresses on these downlevel versions of Windows.

v3.40 (2 May 2020)

• Added support for International email and internationalized email addresses. To support this email addresses can now be encoded as UTF8 in mail headers. Sender and recipient email addresses are now also punycode encoded during the SMTP conversation. Thanks to Martin Richer for supplying this enhancement.
• Provided new SetDoEHLO and GetDoEHLO methods. This eliminates the need for the DoEHLO method.
• Fixed more Clang-Tidy static code analysis warnings in the code.

v3.39 (25 January 2020)

• Fixed a bug in CPJNSMTPAddress::StringTrim which caused strings of the form "pjna@naughter.com; " to not be parsed correctly. Thanks to Martin Richter for reporting this bug.

v3.38 (8 January 2020)

• Updated copyright details.
• Fixed more Clang-Tidy static code analysis warnings in the code.

v3.37 (20 December 2019)

• Fixed various Clang-Tidy static code analysis warnings in the code.
• Updated initialization of various structs to use C++ 11 list initialization.

v3.36 (14 April 2019)

• Replaced BOOL with bool throughout the code.

v3.35 (13 April 2019)

• Added a new CPJNSMTPMessage::AddAttachment method. This new method allows you to add a single attachment to a SMTP message. Internally the existing functionality in CPJNSMTPMessage::AddMultipleAttachments now calls this method.
• The return value for the method CPJNSMTPBodyPart::SetFilename has changed from bool to void.
• Removed the Disconnect call from the CPJNSMTPConnection destructor. This prevents the code stalling for up to the m_dwTimeout value. Instead client code is expected to explicitly call the Disconnect method to close the connection. Also improved the sample app code to avoid stalling for m_dwTimeout in the method CPJNSMTPAppDlg::OnSend.

v3.34 (7 April 2019)

• Updated copyright details.
• Fixed some compiler warnings when compiled with Visual Studio 2019
• Removed code which supports the now defunct CPJNSMTP_MFC_EXTENSIONS codepath
• Removed code which supports the now defunct CNTLMCLIENTAUTH_MFC_EXTENSIONS codepath
• Removed code which supports the now defunct CPJNMD5_MFC_EXTENSIONS codepath
• Removed all dependencies on now defunct IDS_PJNSMTP* string resources

v3.33 (27 December 2018)

• Updated some variable names in the sample app.
• Fixed up some further VS 2017 code analysis warnings

v3.32 (26 December 2018)

• Updated PJNSmtp.h file to warn if memory header file is not already included.
• Fix up a number of compile problems when various CPJNSMTP_* preprocessor values are defined

v3.31 (4 December 2018)

• Fixed a number of compiler warnings when using VS 2017 15.9.3

v3.30 (25 August 2018)

• Fixed a number of compiler warnings when using VS 2017 15.8.1
• Added some additional protective #includes to "PJNNTLMAuth.cpp" module

v3.29 (24 June 2018)

• Updated copyright details.
• Fixed a number of C++ core guidelines compiler warnings. These changes mean that the code will now only compile on VC 2017 or later.

11 January 2018

• For those interested Artur Weber has translated the release notes into Portuguese at https://www.homeyou.com/~edu/conjunto-de-classes-c

v3.28 (18 December 2017)

• Updated the code to compile cleanly when _ATL_NO_AUTOMATIC_NAMESPACE is defined.

v3.27 (9 September 2017)

• Replaced CString::operator LPC*STR() calls throughout the codebase with CString::GetString calls.

v3.26 (2 May 2017)

• Fixed a bug in the CNTLMClientAuth::NTLMAuthenticate method when CNTLMCLIENTAUTH_MFC_EXTENSIONS is defined. Thanks to Darron Redman for reporting this issue.

v3.25 (28 April 2017)

• Updated the code to compile cleanly using /permissive-.

v3.24 (14 April 2017)

• Updated copyright details.
• Updated code to compile cleanly on VC 2017

v3.23 (14 November 2016)

• Updated the non MFC code path in CNTLMClientAuth::NTLMAuthenticate to handle a NULL pszUsername parameter being passed. Thanks to Christopher Craft for reporting this issue.
• Removed unnecessary validation of pszUsername & pszPassword parameters in CPJNSMTPConnection::ConnectESMTP. Thanks to Christopher Craft for reporting this issue.
• Added validation of pszUsername & pszPassword parameters in CPJNSMTPConnection::AuthLogin, CPJNSMTPConnection::AuthPlain & CPJNSMTPConnection::AuthCramMD5 methods. Thanks to Christopher Craft for reporting this issue.
• Improved the SAL annotations on the CPJNSMTPConnection::ConnectESMTP method
• Reworked CPJNSMTPBodyPart::ConvertToUTF8 to use ATL::CW2A

v3.22 (13 October 2016)

• Fixed a bug in the declaration of the CPJNSMTPConnection class when the CPJNSMTP_NONTLM preprocessor value is defined. Thanks to Chris Korda for reporting this issue.
• Provided a new overload of the CPJNSMTPBodyPart::AddChildBodyPart method to allow an already heap allocated bodyPart to be added.
• Provided a new overload of the CPJNSMTPBodyPart::InsertChildBodyPart method to allow an already heap allocated bodyPart to be added.
• Made most of the methods of CPJNSMTPBodyPart virtual to allow for easier end user customization of its functionality.
• Provided a new overload of the CPJNSMTPMessage::AddChildBodyPart method to allow an already heap allocated bodyPart to be added.
• Provided a new overload of the CPJNSMTPMessage::InsertChildBodyPart method to allow an already heap allocated bodyPart to be added.
• Made most of the methods of CPJNSMTPMessage virtual to allow for easier end user customization of its functionality.

v3.21 (19 September 2016)

• Added support for XOAUTH2 authentication. For more information about this SMTP authentication mechanism please see https://developers.google.com/gmail/xoauth2_protocol.
• Reworked the CPJNSMTPConnection::AuthPlain to provide the userid in the authorization identity value. This is a more compatible form of the auth request and avoids issues using AuthPlain against the gmail SMTP servers.
• Added Initial Client Response (SASL-IR) support to the AuthLogin, AuthPlain & AuthXOAUTH2 methods. For more information about SASL-IR please see https://tools.ietf.org/html/rfc4959.

v3.20 (19 August 2016)

• Reworked the CPJNSMTPException::GetErrorMessage to not bother putting the last response into the return error message text.
• CPJNSMTPConnection class is now protected inherited from SSLWrappers::CSocket.

v3.19 (17 August 2016)

• Reworked CPJNSMTPConnection class to be inherited from SSLWrappers::CSocket. This allows for easier overloading of the various SSLWrappers class framework virtual functions

v3.18 (11 August 2016)

• Reworked the SMTP classes to optionally compile without MFC. By default the classes now use STL classes and idioms but if you define CWSOCKET_MFC_EXTENSIONS the classes will revert back to the MFC behaviour.
• Reworked the CPJNSMPTBase64Encode class to use ATL::CHeapPtr.
• Reworked the CPJNSMPTQPEncode class to use ATL::CHeapPtr.
• Reworked the CPJNSMPTQEncode class to use ATL::CHeapPtr.
• Added SAL annotations to all the code.
• CPJNSMTPBodyPart::ConvertToUTF8 now internally uses ATL::CHeapPtr.
• The CPJNSMTPMessage::m_CustomHeaders member variable is now public. As such the AddCustomHeader, GetCustomHeader, GetNumberOfCustomHeaders & RemoveCustomHeader methods have been removed.
• Removed unnecessary code which catches and rethrows a CPJNSMTPException exception from the version of CPJNSMTPConnection::SendMessage which sends a message from a memory buffer.
• Reworked the CPJNSMTPMessage::ParseMultipleRecipients method to avoid the use of the C++ new allocator.
• Reworked the CPJNSMTPMessage::AddMultipleAttachments method to avoid the use of the C++ new allocator.
• Reworked the sample app to exercise the SendMessage method which sends from a memory buffer.
• Removed defunct comments about VC 6 in CPJNMD5 class.
• Reworked the CPJNMD5 class to optionally compile without MFC. By default the class now uses STL classes and idioms but if you define CPJNMD5_MFC_EXTENSIONS the classes will revert back to the MFC behaviour.
• Reworked the CNTLMClientAuth class to optionally compile without MFC. By default the class now uses STL classes and idioms but if you define CNTLMCLIENTAUTH_MFC_EXTENSIONS the class will revert back to the MFC behaviour.

v3.17 (12 May 2016)

• Updated copyright details.
• Minor update to the sample app to refer to "SSL / TLS" in the configuration dialog.
• Verfied the code compiles cleanly using VC 2015.

v3.16 (1 June 2015)

• Removed unused CPJNSMTPMessage::ConvertHTMLToPlainText method.
• Removed the linkage in the test app's configuration dialog between sending a message with a HTML body and requiring that the message is MIME encoded.
• Removed the code from the test app which added a plain text attachment to the message in debug builds.
• Updated CPJNSMTPMessage::AddHTMLBody to handle the case where the message is not MIME encoded. In this case the root body part of the message is simply set to HTML. Thanks to Thane Hubbell for reporting this issue.

v3.15 (29 March 2015)

• Updated CPJNSMTPConnection::AuthLogin to handle more variants of "username:" and "password:" SMTP server responses. Thanks to Wang Le for reporting this issue.

v3.14 (1 March 2015)

• The DoEHLO method has been updated to check for DSN requirements. This change means that the code will connect with a EHLO instead of HELO when a DSN is requested. The code will now also check whether DSN's are supported by the server when attempting to send the DSN. If the server does not support DSN's in this scenario then a new custom exception will be thrown by the code in the CPJNSMTPConnection::FormMailFromCommand method. This ensures the code behaves more consistently with respect to the DSN RFC. Thanks to Philip Mitchell for prompting this update.
• Change the enum value for CPJNSMTPMessage::DSN_NOT_SPECIFIED to 0 from 0xFFFFFFFF.

v3.13 (31 January 2015)

• Fixed an error in CPJNSMTPException::GetErrorMessage where it would not use the full HRESULT value when calling FormatMessage. Thanks to Bostjan Erzen for reporting this issue.
• Improved the error handling in CPJNSMTPConnection::Connect when SSL connection errors occur. Thanks to Bostjan Erzen for reporting this issue.
• Improved the error handling in CPJNSMTPConnection::DoSTARTTLS when SSL connection errors occur. Thanks to Bostjan Erzen for reporting this issue.

v3.12 (25 January 2015)

• Addition of CPJNSMTPBodyPart::InsertChildBodyPart and CPJNSMTPMessage::InsertBodyPart methods. These new methods inserts a body part as the first element in the hierarchy of child body parts instead of to the end. In addition the CPJNSMTPMessage::AddTextBody and CPJNSMTPMessage::AddHTMLBody methods now call CPJNSMTPBodyPart::InsertChildBodyPart instead of CPJNSMTPBodyPart::AddChildBodyPart to ensure that the body text part of the SMTP message appears as the first child body part. This helps avoid issues where Microsoft Exchange modifies multipart messages where the body text is moved to an attachment called ATT00001: For further information please see http://kb.mit.edu/confluence/pages/viewpage.action?pageId=4981187 and http://support2.microsoft.com/kb/969854. Thanks to Marco Veldman for reporting this issue.
• Removed support for DTLSv1 SSL protocol as this is not applicable to SMTP as DTLS is designed for UDP and not TCP. This removal helps resolve an issue where the code did not compile in VC 2013 if you used the "Visual Studio 2013 - Windows XP (v120_xp)" Platform Toolset. Thanks to Bostjan Erzen for reporting this issue.

v3.11 (16 January 2015)

• Updated copyright details
• CPJNSMTPMessage::m_ReplyTo is now an array instead of a single address. Thanks to Bostjan Erzen for suggesting this update.

v3.10 (16 December 2014)

• Updated the code to use the latest v1.03 version of SSLWrappers

v3.09 (14 December 2014)

• Updated the code to use the author's SSLWrappers classes (http://www.naughter.com/sslwrappers.html) to provide the SSL functionality for PJNSMTP instead of OpenSSL. Please note that the SSLWrappers classes itself depends on the author's CryptoWrappers classes (http://www.naughter.com/cryptowrappers.html) also. You will need to download both of these libraries and copy their modules into the PJNSMTP directory. Also note that the SSLWrappers and CryptoWrapper classes are only supported on VC 2013 or later and this means that the PJNSMTP SSL support is only supported when you compile with VC 2013 or later. The solution files included in the download is now for VC 2013.
• With the change to using SSLWrappers, the code can now support additional flavours of SSL protocol. They are: SSL v2 on its own, SSL v3 on its own, The OS SChannel SSL default and AnyTLS. Please see the CPJNSMTPConnection::SSLProtocol enum for more details. The sample app has been updated to allow these values to be used and the default enum value is now "OSDefault".

v3.08 (18 November 2014)

• Fixed a bug in CPJNSMTPBodyPart::GetBody where file attachments were always being treated as 0 in size. Thanks to Oliver Pfister for reporting this issue.

v3.07 (15 November 2014)

• CNTLMClientAuth now takes a static dependency on Secure32.dll instead of using GetProcAddress.
• The CNTLMClientAuth now calls QuerySecurityPackageInfo to determine the buffer size to use.
• The SEC_SUCCESS macro has now been made a method called "SEC_SUCCESS".
• General cleanup of the CNTLMClientAuth::GenClientContext method
• Made the CNTLMClientAuth destructor virtual.
• Removed the defunct method CPJNSMTPBodyPart::HexDigit.
• Reworked the CPJNSMTPBodyPart::GetBody method to use ATL::CAtlFile and ATL::CHeapPtr
• CPJNSMTPConnection now takes a static dependency on Wininet.dll instead of using GetProcAddress.
• CPJNSMTPConnection now takes a static dependency on Dnsapi.dll instead of using GetProcAddress.
• The default timeout set in the CPJNSMTPConnection constructor is now 60 seconds for both debug and release builds
• Removed the now defunct CPJNSMTPConnection::MXLookupAvailable method
• Removed the now defunct CPJNSMTP_NOMXLOOKUP preprocessor value
• Removed the now defunct PJNLoadLibraryFromSystem32.h module from the distribution
• CPJNSMTPConnection::SendMessage has been reworked to use ATL::CAtlFile and ATL::CHeapPtr
• CPJNSMTPConnection::SendMessage now does a UTF-8 conversion on the body of the email when sending a plain email i.e. no HTML or mime if the charset is UTF-8. Thanks to Oliver Pfister for reporting this issue.
• Sample app has been updated to compile cleanly on VS 2013 Update 3 and higher
• The sample app shipped with the source code is now Visual Studio 2008 and as of this release the code is only supported on Visual Studio 2008 and later
• The sample app is now linked against the latest OpenSSL v1.0.1j dlls

v3.06 (13 April 2014)

• The sample app is now linked against the latest OpenSSL v1.0.1g dlls. This version is the patched version of OpenSSL which does not suffer from the Heartbleed bug.
• Please note that by default OpenSSL does not do host name validation. The sample app provided with the PJNSMTP code also does not do host name validation. This means that as it stands the sample app is vulnerable to man in the middle attacks if you use SSL/TLS to connect to a SMTP server. For further information and sample code which you should incorporate into your real SMTP client applications, please see http://wiki.openssl.org/index.php/Hostname_validation, https://github.com/iSECPartners/ssl-conservatory and http://archives.seul.org/libevent/users/Feb-2013/msg00043.html.

v3.05 (9 February 2014)

• Fixed a compile problem in the CreateSSLSocket method when the CPJNSMTP_NOSSL preprocessor macro is defined.
• Reworked the logic which does SecureZeroMemory on sensitive string data 

v3.04 (26 January 2014)

• Updated ASSERT logic at the top of the ConnectESMTP method. Thanks to Jean-Christophe Voogden for reporting this issue.

v3.03 (5 January 2014)

• The ConvertToUTF8 method now also handles conversion of ASCII data to UTF8. Thanks to Jean-Christophe Voogden for this update.
• The CPJNSMTPConnection class now provides Set/GetSSLProtocol methods. This allows client code to specify the exact flavour of SSL which the code should speak. Supported protocols are SSL v2/v3, TLS v1.0, TLS v1.1, TLS v1.2 and DTLS v1.0. This is required for some SMTP servers which use the SSLv2 or v3 protocol instead of the more modern TLS v1 protocol. The default is to use TLS v1.0. You may need to use this compatibility setting for the likes of IBM Domino SMTP servers which only support the older SSLv2/v3 setting. Thanks to Jean-Christophe Voogden for this update.
• Removed all the proxy connection methods as they cannot be easily supported / tested by the author.
• Reworked the code in CPJNSMTPConnection::ConnectESMTP to handle all variants of the 250 response as well as operate case insensitively which is required by the ESMTP RFC.
• Made more methods virtual to facilitate further client customisation
• Fixed an issue in the DoSTARTTLS method where the socket would be left in a connected state if SSL negotiation failed. This would result in later code which sent on the socket during the tear down phase hanging. Thanks to Jean-Christophe Voogden for reporting this issue.
• The sample app is now linked against the latest OpenSSL v1.0.1f dlls.

v3.02 (5 January 2014)

• Updated copyright details.
• Updated the code to clean compile on VC 2013
• Fixed a problem with NTLM auth where the code did not correctly set the "m_nSize" parameter value correctly in CPJNSMPTBase64Encode::Encode & Decode. Thanks to John Pendleton for reporting this bug.

7 June 2013

• Minor update to the sample app to fix a spelling mistake in the connection type string in the configuration dialog. Thanks to "don" for reporting this issue.

v3.01 (3 June 2013)

• The demo app now disables the MIME checkbox after checking it if the email is to be sent as HTML.
• Fixed a bug in the sample app where the mime type of the root body part would be incorrectly set to an empty string when it should use the default which is "multipart/mixed". Thanks to Ting L for reporting this bug. 

v3.00 (12 March 2013)

• Updated copyright details.
• CPJNSMTPAddressArray typedef is now defined in the CPJNSMTPMessage class instead of in the global namespace. In addition this typedef class is now known as "CAddressArray"
• The sample project included in the download now links to the various OpenSSL libraries via defines in stdafx.h instead of via project settings. Thanks to Ed Nafziger for suggesting this nice addition.
• The sample app no longer adds the author's hotmail address to the list of MDN's. Thanks to Ed Nafziger for spotting this.
• The sample app is now linked against the latest OpenSSL v1.0.1e dlls.
• Sample app now statically links to MFC

v2.99 (25 November 2012)

• Fixed some issues in the code when CPJNSMTP_NOSSL was defined. Looks like support for compiling without SSL support has been broken for a few versions. Thanks to Bostjan Erzen for reporting this issue.

v2.98 (30 September 2012)

• Updated the code to avoid DLL planting security issues when calling LoadLibrary. Thanks to Mat Berchtold for reporting this issue.
• A header file called "PJNLoadLibraryFromSystem32.h" is now included which provides a version of LoadLibrary which loads a DLL without any path information from the Windows System directory. This helps avoid DLL planting security issues in your application when you call LoadLibrary with a module name without any path information.

v2.97 (24 September 2012)

• Removed an unnecessary line of code from CPJNSMTPConnection::SendRCPTForRecipient. Thanks to Mat Berchtold for reporting this issue. 

v2.96 (23 September 2012)

• Removed SetContentBase and GetContentBase methods as Content-Base header is deprecated from MHTML. For details see http://www.ietf.org/mail-archive/web/apps-discuss/current/msg03220.html. Thanks to Mat Berchtold for reporting this issue.
• Removed the now defunct parameter from the AddHTMLBody method.
• Removed the FoldHeader method as it was only used by the m_sXMailer header.
• Updated the logic in the FolderSubjectHeader method to correctly handle the last line of text to fold.

v2.95 (12 August 2012)

• STARTTLS support code now uses TLSv1_client_method OpenSSL function instead of SSLv23_client_method. This fixes a problem where sending emails using Hotmail / Windows Live was failing.
• CPJNSMTPConnection::_Close now provides a bGracefully parameter
• Updated the code to clean compile on VC 2012
• The sample app is now linked against the latst OpenSSL v1.0.1c dlls.
• SendMessage now throws a CPJNSMTPException if OnSendProgress returns FALSE.
• Addition of a new ConnectionType called "AutoUpgradeToSTARTTLS" which will automatically upgrade a plain text connection to STARTTLS if the code detects that the SMTP server supports STARTTLS. If the server doesn't support STARTTLS then the connection will remain as if you specified "PlainText"
• Reworked the code to determine if it should connect using EHLO instead of HELO into a new virtual method called DoEHLO.
• Reworked the internals of the ConnectESMTP method.

v2.94 (4 December 2011)

• Updated CPJNSMTPBodyPart::GetHeader to encode the title of a filename if it contains non-ASCII characters. Thanks to Anders Gustafsson for reporting this issue.
• The sample app is now linked against the latst OpenSSL v1.0.0e dlls.  

v2.93 (1 April 2011)

• Reintroduced the concept of Address Header encoding. By default this setting is off, but can be enabled via a new CPJNSMPTMessage::m_bAddressHeaderEncoding boolean value. Thanks to Bostjan Erzen for reporting this issue.
• The sample app is now linked against the latest OpenSSL v1.0.0d dlls

v2.92 (13 February 2011)

• Remove the IP binding address parameter from the Connect method as there was already support for binding via the Set/GetBoundAddress methods.
• Set/GetBoundAddress have been renamed Set/GetBindAddress for consistency with the sockets class

v2.91 (8 February 2011)

• Updated copyright details
• Updated code to support latest SSL and Sockets class from the author. This means that the code now supports IPv6 SMTP servers
• Connect method now allows binding to a specific IP address

v2.90 (18 December 2010)

• Removed the methods Set/GetQuotedPrintable and Set/GetBase64 from CPJNSMTPBodyPart and replaced them with new Set/GetContentTransferEncoding methods which works with a simple enum.
• CPJNSMTPBodyPart::SetAttachment and CPJNSMTPBodyPart::SetFilename now automatically sets the Content-Transfer-Encoding to base64 for attachments. Thanks to Christian Egging for reporting this issue.
• The sample app is now linked against the latest OpenSSL v1.0.0c dlls

v2.89 (28 November 2010)

• AddTextBody and AddHTMLBody now allow the root body part's MIME type to be changed. Thanks to Thane Hubbell for prompting this update.
• Added a CPJNSMTPBodyPart::GetBoundary method.
• Added some sample code to the sample app's CPJNSMTPAppDlg constructor to show how to create a message used SMTP body parts. Thanks to Thane Hubbell for prompting this update.
• CPJNSMTPBodyPart::GetHeader now allows quoted-printable and raw attachments to be used
• The sample app is now linked against the latest OpenSSL v1.0.0b dlls

v2.88 (10 July 2010)

• Following feedback from multiple users of PJNSMTP, including Chris Bamford and "loggerlogger", the change from "multipart/mixed" to "multipart/alternative" has now been reverted. Using "multipart/mixed" is a more appropriate value to use. Testing by various clients have shown that this setting works correctly when sending HTML based email in GMail, Thunderbird and Outlook. Unfortunately this is the price I must pay when accepting end user contributions to my code base which I cannot easily test. Going forward I plan to be much more discerning on what modifications I will accept to avoid these issues.
• The CPJNSMTPBodyPart now has the concept of whether or not the body is considered an attachment. Previously the code assumed that if you set the m_sFilename parameter that the body part was an attachment. Instead now the code uses the "m_bAttachment" member variable. This allows an in memory representation of an attachment to be added to a message without the need to write it to an intermediate file first. For example, here would be the series of steps you would need to go through to add an in memory jpeg image to an email and have it appear as an attachment:
  
  const BYTE* pInMemoryImage = pointer to your image;
  DWORD dwMemoryImageSize = size in bytes of pInMemoryImage;
  CPJNSMPTBase64Encode encode;
  encode.Encode(pInMemoryImage, dwMemoryImageSize, ATL_BASE64_FLAG_NONE);
  CPJNSMTPBodyPart imageBodyPart;
  imageBodyPart.SetRawBody(encode.Result());
  imageBodyPart.SetBase64(TRUE);
  imageBodyPart.SetAttachment(TRUE);
  imageBodyPart.SetContentType(_T("image/jpg"));
  imageBodyPart.SetTitle(_T("the name of the image"));
  CPJNSMTPMessage message;
  message.AddBodyPart(imageBodyPart);
  
  Thanks to Stephan Eizinga for suggesting this nice addition. 

v2.87 (4 June 2010)

• Updated the code and sample app to compile cleanly when CPJNSMTP_NOSSL is defined. Thanks to "loggerlogger" for reporting this issue.

v2.86 (23 May 2010)

• Updated copyright details
• Updated sample app to compile cleanly on Visual Studio 2010
• The sample app is now linked against the latest OpenSSL v1.0.0 dlls
• Removed an unused "sRet" variable in CPJNSMTPConnection::AuthCramMD5. Thanks to Alain Danteny for reporting this issue
• Replaced all calls to memcpy with memcpy_s
• The code now supports STARTTLS encryption as defined in RFC 3207
• If the call to DnsQuery fails, the error value is now preserved using SetLastError
• AddTextBody now sets the mime type of the root body part multipart/alternative. This is a more appropriate value to use which is better supported by more email clients. Thanks to Thane Hubbell for reporting this issue.

v2.85 (17 December 2009)

• The sample app is now linked against the latest OpenSSL v0.9.8l dlls
• Updated the sample code in the documentation to better describe how to use the various classes. Thanks to Dionisis Kofos for reporting this issue.

v2.84 (13 November 2009)

• Now includes comprehensive support for MDN's (Message Disposition Notifications) as specified in RFC 3798. Thanks to Ron Brunton for prompting this update.
• Rewrote CPJNSMTPMessage::SaveToDisk method to use CAtlFile

v2.83 (28 June 2009)

• Updated copyright details
• Fixed a bug where the Reply-To email address was not correctly added to the message. Thanks to Dmitriy Maksimov for reporting this issue.
• Updated the sample app's project settings to more modern default values.
• Updated the sample exe to ship with OpenSSL v0.98k
• Fixed a bug in CPJNSMTPConnection::SendBodyPart where it would cause errors from OpenSSL when trying to send a body of 0 bytes in size. This can occur when MHTML based emails are sent and you are using a "multipart/related" body part. Thanks to "atota" for reporting this issue

v2.82 (6 November 2008)

• For best compatibility purposes with existing SMTP mail servers, all message headers which include email addresses are now not Q encoded. Thanks to Christian Egging for reporting this issue.
• Optimized use of CT2A class throughout the code

v2.81 (2 November 2008)

• Improvements to CPJNSMTPAddress constructor which takes a single string. The code now removes redundant quotes.
• CPJNSMTPAddress::GetRegularFormat now forms the regular form of the email address before it Q encodes it.
• The sample app now uses DPAPI to encrypt the username & password configuration settings.
• The sample app is now linked against the latest OpenSSL v0.9.8i dlls.
• Updated coding references in the html documentation. In addition the zip file now includes the OpenSSL dlls. Thanks to Michael Grove for reporting this issues.

v2.80 (16 August 2008)

• Updated the AUTH_AUTO login support to fall back to no authentication if no authentication scheme is supported by the SMTP server. Thanks to Mat Berchtold for this update.

v2.79 (27 July 2008)

• Updated code to compile correctly using _ATL_CSTRING_EXPLICIT_CONSTRUCTORS define
• CPJNSMTPMessage::GetHeader now correctly ensures all long headers are properly folded. In addition this function has been reworked to create the header internally as an ASCII string rather than as a TCHAR style CString.

v2.78 (20 July 2008)

• Fixed a bug in ReadResponse where the code is determining if it has received the terminator. Thanks to Tony Cool for reporting this bug.

v2.77 (31 May 2008)

• Code now compiles cleanly using Code Analysis (/analyze)
• Removed the use of the function QuotedPrintableEncode and replaced with ATL::QPEncode
• Removed the use of the function QEncode and replaced with ATL::QEncode
• Reworked ReadResponse to use CStringA in line with the implementation in the POP3 class of the author.

v2.76 (1 March 2008)

• CPJNSMTP Priority enum values, specifically NO_PRIORITY have been renamed to avoid clashing with a #define of the same name in the Windows SDK header file WinSpool.h. The enum values for DSN_RETURN_TYPE have also been renamed to maintain consistency. Thanks to Zoran Buntic for reporting this issue.
• Fixed compile problems related to the recent changes in the Base64 class. Thanks to Mat Berchtold for reporting this issue.
• Since the code is now for VC 2005 or later only, the code now uses the Base64 encoding support from the ATL atlenc.h header file. Thanks to Mat Berchtold for reporting this optimization. This means that client projects no longer need to include Base64.cpp/h in their projects.

v2.75 (2 February 2008)

• Updated copyright details.
• Fixed a bug in CPJNSMTPMessage::FormDateHeader where sometimes an invalid "Date:" header is created. The bug will manifest itself for anywhere that is ahead of GMT, where the difference isn't a multiple of one hour. According to the Windows Time Zone applet, this bug would have occured in: Tehran, Kabul, Chennai, Kolkata, Mumbai, New Delhi, Sri Jayawardenepura, Kathmandu, Yangon, Adelaide and Darwin. Thanks to Selwyn Stevens for reporting this bug and providing the fix.

v2.74 (31 December 2007)

• Updated the sample app to clean compile on VC 2008
• Fixed a x64 compile problems in RemoveCustomHeader & AddMultipleAttachments.
• Fixed a x64 compile problem in CPJNSMTPAppConfigurationDlg::CBAddStringAndData
• CPJNSMTPException::GetErrorMessage now uses Checked::tcsncpy_s
• Other Minor coding updates to CPJNSMTPException::GetErrorMessage

v2.73 (24 December 2007)

• CPJNSMTPException::GetErrorMessage now uses the FORMAT_MESSAGE_IGNORE_INSERTS flag. For more information please see Raymond Chen's blog at http://blogs.msdn.com/oldnewthing/archive/2007/11/28/6564257.aspx. Thanks to Alexey Kuznetsov for reporting this issue.
• All username and password temp strings are now securely destroyed using SecureZeroMemory.

v2.72 (23 December 2007)

• Following feedback from Selwyn Stevens that the AUTH PLAIN mechanism was failing for him while trying to send mail using the gmail SMTP server, I decided to go back and re-research the area of SMTP authentication again<g>. It turns out that the way I was implementing AUTH PLAIN support was not the same as that specified in the relevant RFCs. The code has now been updated to be compliant with that specified in the RFC. I've confirmed the fix as operating correctly by using the gmail SMTP mail server at "smtp.gmail.com" on the SMTP/SSL port of 465. I've also taken the opportunity to update the documentation to include a section with links to various RFC's and web pages for background reference material

v2.71 (19 November 2007)

• The "Date:" header is now formed using static lookup arrays for the day of week and month names instead of using CTime::Format. This helps avoid generating invalid Date headers on non English version of Windows where the local language versions of these strings would end up being used. Thanks to feedback at the codeproject page for the code (specifically http://www.codeproject.com/internet/csmtpconn.asp?df=100&forumid=472&mpp=50&select=2054493#xx2054493xx for reporting this issue).

v2.70 (13 November 2007)

• Major update to the code to use VC2005 specific features. This version of the code and onwards will be supported only on VC 2005 or later. Thanks to Andrey Babushkin for prompting this update. Please note that there has been breaking changes to the names and layout of various methods and member variables. You should carefully analyze the sample app included in the download as well as your client code for the required updates you will need to make.
• Sample app included in download is now build for Unicode and links dynamically to MFC. It also links dynamically to the latest OpenSSL 0.9.8g dlls.

v2.67 (1 August 2007)

• AuthCramMD5, ConnectESMTP, ConnectSMTP, AuthLogin, and AuthPlain methods have now been made virtual.
• Now includes support for a Auto Authentication protocol. This will detect what authentication methods the SMTP server supports and uses the "most secure" method available. If you do not agree with the order in which the protocol is chosen, a virtual function called "ChooseAuthenticationMethod" has been provided. Thanks to "zhangbo" for providing this very nice addition to the code.
• Removed the definition for the defunct "AuthNTLM" method.

v2.66 (30 March 2007)

• Fixed a bug in CPJNSMTPConnection::SetHeloHostname where an unitialized stack variable could potentially be used. Thanks to Anthony Kowalski for reporting this bug.
• Updated copyright details.

v2.65 (11 November 2006)

• Reverted CPJNSMTPException::GetErrorMessage to use the system default locale. This is consistent with how MFC does its own error handling.
• Now includes comprehensive support for DSN's (Delivery Status Notifications) as specified in RFC 3461. Thanks to Riccardo Raccuglia for prompting this update.
• CPJNSMTPBodyPart::GetBody and CPJNSMTPConnection::SendMessage(const CString& sMessageOnFile... now does not open the disk file for exclusive read access, meaning that other apps can read from the file. Thanks to Wouter Demuynck for reporting this issue.
• Fixed an issue in CPJNSMTPConnection::SendMessage(const CString& sMessageOnFile... where under certain circumstances we could end up deleting the local "pSendBuf" buffer twice. Thanks to Izidor Rozman for reporting this issue.

v2.64 (13 October 2006)

• Code now initializes the Domain name value in CNTLMClientAuth::NTLMAuthenticate to an empty string instead of a NULL string. This avoids NTLM authentication issues when authenticating as a non-domain user with certain mail servers. Thanks to Wouter Demuynck for reporting this issue.
• Fixed an issue in Disconnect where if the call to ReadCommandResponse threw an exception, we would not close down the socket or set m_bConnected to FALSE. The code has been updated to ensure these are now done. This just provides a more consistent debugging experience. Thanks to Alexey Kuznetsov for reporting this issue.
• CPJNSMTPException::GetErrorMessage now uses the user default locale for formatting error strings.
• Fixed some issues with cleaning up of header and body parts in CPJNSMTPConnection::SendBodyPart and CPJNSMTPMessage::WriteToDisk. Thanks to Xiao-li Ling for reporting this issue.

17 July 2006

• Updated the code in the sample app to allow > 30000 characters to be entered into the edit box which contains the body of the email. This is achieved by placing a call to CEdit::SetLimitText in the OnInitDialog method of the dialog. Thanks to Thomas Noone for reporting this issue.

v2.63 (14 July 2006)

• Fixed a bug in CPJNSMTPConnection where when compiled in UNICODE mode, NTLM authentication would fail. Thanks to Wouter Demuynck for providing the fix for this bug.
• Reworked the CPJNSMTPConnection::NTLMAuthPhase(*) methods to throw standard CPJNSMTPException exceptions if there are any problems detected. This can be done now that the CNTLMClientAuth class is resilient to exceptions being thrown.
• Updated CNTLMClientAuth to use newer C++ style casts.
• Made the CNTLMClientAuth::NTLMAuthenticate function "exception" safe, that is derived classes are free to throw exceptions in their implementations of NTLMAuthPhase1, NTLMAuthPhase2 or NTLMAuthPhase3 and the CNTLMClientAuth class will properly clean up its resources. This is achieved by making the CredHandle and SecHandle values member variables of the class.
• Replaced all calls to ZeroMemory with memset.
• Now the public NTLMAuthenticate function allows you to pass a user name and password pair to do NTLM authentication using a specified account instead of the credentials of the current user. If you leave these values as NULL, then you will get the old behaviour which is to use the current user credentials. Thanks to Wouter Demuynck for this very nice addition.

v2.62 (29 June 2006)

• Updated the documentation to use the same style as the web site.
• Combined the functionality of the _PJNNTLMCLIENTAUTH_DATA class into the main CNTLMClientAuth class.
• Code now uses new C++ style casts rather than old style C casts where necessary.
• Integrated ThrowPJNSMTPException function into CPJNSMTPConnection class and renamed to ThrowPJNSMTPException
• Combined the functionality of the _PJNSMTP_DATA class into the main CPJNSMTPConnection class.
• Updated the code to clean compile on VC 2005
• Updated copyright details.
• Removed unnecessary checks for failure to allocate via new since in MFC these will throw CMemoryExceptions!.
• Optimized CPJNSMTPException constructor code

9 December 2005

• Updated the usage section of the documentation on how to correctly exclude the SSL functionality from the class. Thanks to Berni Slootbeek for prompting this update.
• Updated the usage section of the documentation on the preferred way of formatting CID tags for MHTML emails. Thanks to Asle Rokstad for prompting this update.

v2.61 (16 November 2005)

• Now includes full support for connecting via SSL. For example sending mail thro Gmail using the server "smtp.gmail.com" on port 465. Thanks to Vladimir Sukhoy for providing this very nice addition (using of course the author's very own OpenSSL wrappers!).

v2.60 (7 October 2005)

• Fixed an issue where file attachments were incorrectly including a charset value in their headers. Thanks to Asle Rokstad for reporting this issue.

v2.59 (2 October 2005)

• MXLookup functionality of the class can now be excluded via the preprocessor define "CPJNSMTP_NOMXLOOKUP". Thanks to Thiago Luiz for prompting this update. 
• Sample app now does not bother asking for username and password if authentication type is NTLM. Thanks to Emir Kapic for spotting this issue.
• Documentation has been updated to refer to issues with NTLM Authentication and SSPI. Thanks to Emir Kapic for prompting this update.
• Fixed an update error done for the previous version which incorrectly supported the additional 251 command for the "MAIL" command instead of more correctly the "RCPT" command. Thanks to Jian Peng for reporting this issue.

v2.58 (29 September 2005)

• Removed linkage to secur32.lib as all SSPI functions are now constructed at runtime using GetProcAddress. Thanks to Emir Kapic for this update.
• MD5 Format method now allows you to specify an uppercase or lower case string for the hash. This is necessary since the CRAM-MD5 authentication mechanism requires a lowercase MD5 hash. Thanks to Jian Peng for reporting this issue.
• 250 or 251 is now considered a successful response to the RCPT command. Thanks to Jian Peng for reporting this issue.
• Fixed potential memory leaks in the implementation of NTLM authentication as the code was throwing exceptions which the authentication code was not expected to handle.

v2.57 (7 September 2005)

• Fixed another single dot issue, this time where the body is composed of just a single dot. Thanks to Raimund Mettendorf for reporting this issue.
• Fixed a typo in the accessor function CPJNSMTPConnection::GetBoundAddress which was incorrectly called CPJNSMTPConnection::SetBoundAddress. Thanks to Pavel Kolar for reporting this.

v2.56 (5 September 2005)

• Fixed an issue in MXLookup method where memory was not being freed correctly in the call to DnsRecordListFree. Thanks to Raimund Mettendorf for reporting this bug.
• Fixed an issue where lines which had a single dot i.e. "." did not get mailed correctly. Thanks to Raimund Mettendorf for reporting this issue.
• Removed the call to FixSingleDot from SetText method as it is done at runtime as the email as being sent. This was causing problems for fixing up the dot issue when MIME encoded messages were being sent.
• Function pointer to CompleteAuthToken is now constructed at runtime. This means that NTLM client authentication will work correctly on Win9x as used by the class CPJNSMTPConnection and any other class instead of bringing up a "Failed to load due to missing export..." message from the Windows loader. If you want to remove the NTLM support from CPJNSMTPConnection then you can continue to use the CPJNSMTP_NONTLM preprocessor define. Thanks to "Lior" for reporting this problem.
• Fixed an issue where the FixSingleDot function was being called when saving a message to disk. This was incorrect and it should only be done when actually sending an SMTP email.

v2.55 (14 August 2005)

• Minor update to include comments next to various locations in the code to inform users what to do if they get compile errors as a result of compiling the code without the Platform SDK being installed. Thanks to Gudjon Adalsteinsson for prompting this update.
• Fixed an issue when the code calls the function DnsQuery when the code is compiled for UNICODE. This was the result of a documentation error in the Platform SDK which incorrectly says that DnsQuery_W takes a ASCII string when in actual fact it takes a UNICODE string. Thanks to John Oustalet III for reporting this issue.

v2.54 (24 July 2005)

• Now includes support for parsing "(...)" comments in addresses. Thanks to Alexey Kuznetsov for this nice addition.
• Fixed an issue where the mail header could contain a "Content-Transfer-Encoding" header. This header should only be applied to headers of MIME body parts rather than the mail header itself. Thanks to Jeroen van der Laarse, Terence Dwyer and Bostjan Erzen for reporting this issue and the required fix.
• Now calling both AddTextBody and AddHTMLBody both set the root body part MIME type to multipart/mixed. Previously the code comments said one thing and did another (set it to "multipart/related"). Thanks to Bostjan Erzen for reporting this issue.

18 May 2005

• Fixed a compiler warning in the CPJNMD5Hash class when compiled using Visual Studio .NET 2003. Thanks to Alexey Kuznetsov for reporting this issue.

v2.53 (3 May 2005)

• Updated the usage section to describe the need to have the Platform SDK installed and configured.
• Fixed a number of warnings when the code is compiled in Visual Studio .NET 2003. Thanks to Nigel Delaforce for reporting these issues.

v2.52 (1 May 2005)

• Now uses the author's CWSocket sockets wrapper class.
• Added support for connecting via Socks4, Socks5 and HTTP proxies 
• The last parameter to Connect has now been removed and is configured via an accessor / mutator pair Get/SetBoundAddress.
• CSMTPException class is now called CPJNSMTPException.
• Class now uses the Base64 class as provided with CWSocket. This means that the modules Base64Coder.cpp/h are no longer distributed or required and should be removed from any projects which use the updated SMTP classes.
• Fixed a bug in SaveToDisk method whereby existing files were not being truncated prior to saving the email message.
• All calls to allocate heap memory now generate a CPJNSMTPException if the allocation fails.
• Addition of a MXLookupAvailable() function so that client code can know a priori if DNS MX lookups are supported.
• Sample app now allows you to use the MXLookup method to determine the mail server to use based on the first email address you provide in the To field.

v2.51 (23 April 2005)

• The code now uses a MS Crypto API implementation of the MD5 HMAC algorithm instead of custom code based on the RSA MD5 code. This means that there is no need for the RSA MD5.cpp, MD5.h and glob-md5.h to be included in client applications. In addition the build configurations for excluding the RSA MD5 code has been removed from the sample app. The new classes to perform the MD5 hashing are contained in PJNMD5.h and are generic enough to be included in client applications in their own right.

v2.50 (18 April 2005)

• Addition of a simple IsConnected() function inline with the author's CPop3Connection class. Thanks to Alexey Kuznetsov for prompting this addition.
• Addition of a MXLookup function which provides for convenient DNS lookups of MX records (the IP addresses of SMTP mail servers for a specific host domain). Internally this new function uses the new DNS functions which are provided with Windows 2000 or later. To ensure that the code continues to work correctly on earlier versions of Windows, the function pointers for the required functions are constructed at runtime using GetProcAddress. You can use this function to discover the IP address of the mail servers responsible for a specific domain. This allows you to deliver email directly to a domain rather than through a third party mail server. Thanks to Hans Dietrich for suggesting this nice addition.

v2.49 (26 March 2005)

• Fixed compile problems with the code when the Force Conformance In For Loop Scope compile setting is used in Visual Studio .NET 2003. Thanks to Alexey Kuznetsov for reporting this problem.
• Fixed compile problems when the code is compiled using the Detect 64-bit Portability Issues setting in Visual Studio .NET 2003.

v2.48 (7 March 2005)

• Addition of PJNSMTP_EXT_CLASS define to the classes to allow the classes to be easily incorporated into extension DLLs. Thanks to Arnaud Faucher for suggesting this addition.
• Now support NTLM authentication. Thanks to Arnaud Faucher for this nice addition. NTLM Authentication is provided by a new reusable class called "CNTLMClientAuth" in PJNNTLMAuth.cpp/h".
• Fixed a bug in the sample app in the persistence of the Authentication setting. Thanks to Arnaud Faucher for reporting this issue.

19 February 2005

• Updated the usage section of the documentation to describe what is required to integrate the code into your applications. Thanks to Matthew Tompkins for prompting this update.

v2.47 (24 January 2005)

• All classes now uses exceptions to indicate errors. This means the whole area of handling errors in the code a whole lot simpler. For example the OnError mechanism is gone along with all the string literals in the code. The actual code itself is a whole lot simpler also. You should carefully review your code as a lot of the return values from methods (especially CPJNSMTPConnection) are now void and will throw CSMTPException's. Thanks to Mark Smith for prompting this update.
• General tidy up of the code following the testing of the new exception based code.

v2.46 (23 December 2004)

• "Name" field in Content-Type headers is now quoted just like the filename field. Thanks to Mark Smith for reporting this issue in conjunction with the mail client Eudora.

v2.45 (30 September 2004)

• Fixed a parsing issue in CPJNSMTPConnection::ReadResponse when multi line responses are read in as multiple packets. Thanks to Mark Smith for reporting this problem.
• Reworked the code which supports the various authentication mechanisms to support the correct terms. What was called "AUTH LOGIN PLAIN" support now more correctly uses the term "AUTH PLAIN". The names of the functions and enums have now also been reworked.
• Did a review of the sample app code provided with the class so that the name of the modules, projects, exe etc is now "PJNSMTPApp". Also reworked the name of some helper classes as well as the module name which supports the main class.
• Reworked CPJNSMTPConnection::AuthLoginPlain (now called AuthPlain) to correctly handle the case where an invalid response is received when expecting the username: response. Thanks to Mark Smith for reporting this problem.

v2.44 (7 June 2004)

• Fixed a potential buffer overflow issue in CSMTPConnection::ReadResponse when certain multi line responses are received

v2.43 (5 June 2004)

• Fixed a bug in CSMTPConnection::ReadResponse, where the wrong parameters were being null terminated. Thanks to "caowen" for this update.
• Updated the CSMTPConnection::ReadResponse function to handle multiline responses in all cases. Thanks to Thomas Liebethal for reporting this issue.

v2.42 (13 March 2004)

• Fixed a problem where the CSMTPBodyPart::m_dwMaxAttachmentSize value was not being copied in the CSMTPBodyPart::operator= method. Thanks to Gerald Egert for reporting this problem and the fix.

v2.41 (4 March 2004)

• To avoid conflicts with the ATL Server class of the same name, namely "CSMTPConnection", the class is now called "CPJNSMTPConnection". To provide for easy upgrading of code, "CSMTPConnection" is now defined to be "CPJSMTPConnection" if the code detects that the ATL Server SMTP class is not included. Thanks to Ken Jones for reporting this issue.

v2.40 (18 February 2004)

• You can now optionally set the priority of an email thro the variable CSMTPMessage::m_Priority. Thanks to Edward Livingston for suggesting this addition.

v2.39 (7 February 2004)

• Fixed a bug in CSMTPBodyPart::SetText where the code would enter an endless loop in the Replace function. It has now been replaced with CString::Replace. This now means that the class will not now compile on VC 5. Thanks to Johannes Philipp Grohs for reporting this problem.
• Fixed a number of warnings when the code is compiled with VC.Net 2003. Thanks to Edward Livingston for reporting this issue.

v2.38 (31 January 2004)

• Fixed a bug in CSMTPBodyPart::GetBody where the size of the body part was incorrectly calculating the size if the encoded size was an exact multiple of 76. Thanks to Kurt Emanuelson and Enea Mansutti for reporting this problem.

v2.37 (11 December 2003)

• Fixed an unreferrenced variable in CPJNSMTPConnection::OnError as reported by VC.Net 2003
• DEBUG_NEW macro is now only used on VC 6 and not on VC 7 or VC 7.1. This avoids a problem on these compilers where a conflict exists between it and the STL header files. Thanks to Alex Evans for reporting this problem.

v2.36 (3 December 2003)

• Made code which checks the Login responses which contain "Username" and "Password" case insensitive. Thanks to Zhang xiao Pan for reporting this problem.

v2.35 (3 November 2003)

• Simplified the code in CPJNSMTPConnection::ReadResponse. Thanks to Clarke Brunt for reporting this issue.

v2.34 (15 October 2003)

• Reworked the CPJNSMTPConnection::ReadResponse method to use the timeout provided by IsReadable rather than calling sleep. Thanks to Clarke Brunt for reporting this issue.

19 August 2003

• Updated the sample app to avoid a memory leak. It turns out that it was to do with the ordering of <string> in the pre compiled header. I was never too fond of STL and this has confirmed my prejudices.  Thanks to Damian Willis for reporting this problem.

v2.33 (18 August 2003)

• Modified the return value from the ConnectToInternet method. Instead of it being a boolean, it is now an enum. This allows client code to differentiate between two conditions that it couldn't previously, namely when an internet connection already existed or if a new connection (presumably a dial-up connection was made). This allows client code to then disconnect if a new connection was required. Thanks to Pete Arends for this nice addition.

18 August 2003

• Christian Andersen has taken the CPJNSMTPConnection class and developed a version runs on Windows CE. The code can be downloaded here. I would ask you to forward any queries relating to this code to Christian as I am only hosting the code as a favor to him.

v2.32 (12 May 2003)

• Fixed a bug where the X-Mailer header was being sent incorrectly. Thanks to Paolo Vernazza for reporting this problem.
• Addition of X-Mailer header is now optional. In addition sample app now does not send the X-Mailer header.
• The sample app now does not send the Reply-To header.

v2.31 (5 May 2003)

• Reworked the way UTF8 encoding is now done. What you should do if you want to use UTF-8 encoding is set the charset  "UTF-8" and use either QP or base 64 encoding.
• Reworked the automatic encoding of the subject line to use the settings as taken from the root SMTP body part
• Only the correct headers according to the MIME RFC are now encoded.
• QP encoding is the encoding mechanism now always used for headers.
• Headers are now only encoded if required to be encoded.

v2.30 (4 May 2003)

• Fixed an issue where the class doesn't convert the mail body and subject to the wanted encoding but rather changes the encoding of the email in the email header. Since the issue of supporting several languages is a complicated one I've decided that we could settle for sending all CPJNSMTPConnection emails in UTF-8. I've added some conversion functions to the class that - at this point - always converts the body and subject of the email to UTF-8. A big thanks to Itamar Kerbel for this nice addition.
• Moved code and sample app to VC 6.

v2.29 (19 April 2003)

• Fixed a bug in the CSMTPAddress constructor where I was mixing up the friendly name in the "<>" separators, when it should have been the email address.

v2.28 (17 April 2003)

• Enhanced the CSMTPAddress constructor to parse out the email address and friendly name rather than assume it is an email address.
• Reworked the syntax of the CSMTPMessage::ParseMultipleRecipients method. Also now internally this function uses the new CSMTPAddress constructor.

v2.27 (13 April 2003)

• Fixed a bug in the handling of EHLO responses. Thanks to "Senior" for the bug report and the fix.

v2.26 (19 March 2003)

• Addition of copy constructors and operator= to CSMTPMessage class. Thanks to Alexey Vasilyev for this suggestion.

9 February 2003

• Updated the sample app to display a simple progress dialog when you send a message from disk (not using the "Send Direct") option. This provides a sample of how you can implement a cancellable send of a message with progress support. Thanks to "nabocorp" for suggesting this addition to the sample.

v2.25 (7 February 2003)

• Addition of a "BOOL bGracefully" argument to Disconnect so that when an application cancels the sending of a message, you can pass FALSE and close the socket without properly terminating the SMTP conversation. Thanks to "nabocorp" for this nice addition.
• Did a spell check on the documentation <g>.

v2.24 (11 December 2002)

• Review all TRACE statements for correctness
• Provided a virtual OnError method which gets called with error information.

v2.23 (4 October 2002)

• Fixed an issue where the header / body separator was not being sent correctly for mails with attachments or when the message is MIME encoded. Thanks to Serhiy Pavlov for reporting this problem.
• Fixed a bug in QuotedPrintableEncode and HeaderEncode which was causing the errors. Thanks to Antonio Maiorano for reporting this problem.
• Fixed an issue with an additional line separator being sent between the header and body of emails. This was only evident in mail clients if a non mime email without attachments was sent.

v2.22 (3 October 2002)

• Quoted printable encoding didn't work properly in UNICODE. (invalid conversion from TCHAR to BYTE). Thanks to Serhiy Pavlov for reporting this problem.
• Subject encoding didn't work properly in UNICODE. (invalid conversion from TCHAR to BYTE). Thanks to Serhiy Pavlov for reporting this problem.
• It didn't insert "charset" tag into root header for plain text messages (now it includes "charset" into plain text messages too). Thanks to Serhiy Pavlov for reporting this problem.

v2.21 (20 September 2002)

• Fixed a problem where the code "Coder.EncodedMessage" was not being converted from an ASCII string to a UNICODE string in calls to CString::Format. This was occurring when sending the username and password for "AUTH LOGIN" support in addition to sending the "username digest" for "AUTH CRAM-MD5" support. Thanks to Serhiy Pavlov for reporting this problem.
• Removed a number of calls to CString::Format and instead replaced with string literal CString constructors instead.

v2.20 (10 August 2002)

• Fixed a number of uncaught file exceptions in CSMTPBodyPart::GetBody, CSMTPMessage::SaveToDisk and CPJNSMTPConnection::SendMessage. Thanks to John Allan Miller for reporting this problem.
• The CPJNSMTPConnection::SendMessage version of the method which sends a file directly from disk, now fails if the file is empty.
• Improved the sample app by displaying a wait cursor while a message from file is being sent.
• Improved the sample app by warning the user if mail settings are missing and then bringing up the configuration dialog.

v2.19 (29 July 2002)

• Fixed an access violation in CSMTPBodyPart::QuotedPrintableEncode. Thanks to Fergus Gallagher for spotting this problem.
• Fixed a problem where in very rare cases, the QuotedPrintableEncode function produces a single dot in a line, when inserting the "=" to avoid the mail server's maxline limit. I inserted a call to FixSingleDot after calling the QuotedPrintableEncode function in GetBody. Thanks to Andreas Kappler for spotting this problem.
• Fixed an issue in CSMTPBodyPart::GetHeader which ensures all mail clients can correctly handle body parts and attachments which have a filename with spaces in it. Thanks to Andreas Kappler for spotting this problem.
• QP encoding is now only used when you specify MIME. This fixes a bug as reported by David Terracino.
• Removed now unused "API Reference" link in HTML file supporting the code.

13 January 2002

• Minor update to the sample app to fix a bug in browsing for attachments, Core classes not changed.

v2.18 (11 January 2002)

• Now includes a method to send a message directly from memory. Thanks to Tom Allebrandi for this suggestion.
• Change function name "IsReadible" to be "IsReadable". I was never very good at English!.
• Fixed a bug in CSMTPBodyPart::QuotedPrintableEncode. If a line was exactly 76 characters long plus \r\n it produced an invalid soft line break of "\r=\r\n\n". Thanks to Gerald Egert for spotting this problem.

3 December 2001

• Included item in copyright about the use of class in bulk mailers.

v2.17 (12 October 2001)

• Fixed a problem where GetBody was reporting the size as 1 bigger than it should have been. Thanks to "c f" for spotting this problem.
• Fixed a bug in the TRACE statements when a socket connection cannot be made.
• The sample app now displays a filter of "All Files" when selecting attachments to send.
• Fixed a problem sending 0 byte attachments. Thanks to Deng Tao for spotting this problem.

v2.16 (29 September 2001)

Eric Fontana has taken the CPJNSMTPConnection class and developed a COM version which has the following features, The code can be downloaded here. I would ask you to forward any queries relating to this code to Eric as I am only hosting the code as a favor to him

• Fixed a bug in ReadResponse which occurred when you disconnected via Dial-Up Networking while a connection was active. This was originally spotted in my POP3 class.
• Fixed a problem in CSMTPBodyPart::GetHeader which was always including the "quoted-printable" even when 
  m_bQuotedPrintable for that body part was FALSE. Thanks to "jason" for spotting this.

• In proc dll COM interface
• Supports IDispatch so can be called from ASP, VBScript, JScript etc

v2.15 (13 August 2001)

• Fixed a bug in QuotedPrintableEncode which was wrapping encoding characters across multiple lines. Thanks to Roy He for spotting this.
• Provided a "SendMessage" method which sends a email directly from disk. This allows you to construct your own emails and the use the class just to do the sending. This function also has the advantage that it efficiently uses memory and reports progress.
• Provided support for progress notification and cancelling via the "OnSendProgress" virtual method.

v2.14 (15 July 2001)

• Improved the error handling in the function CSMTPMessage::AddMultipleAttachments. In addition the return value has been changed from BOOL to int.

v2.13 (1 July 2001)

• Modified QuotedPrintableEncode to prevent the code to enter in an infinite loop due to a long word i.e. bigger than SMTP_MAXLINE, in this case, the word is broken. Thanks to Manuel Gustavo Saraiva for this fix.
• Provided a new protected variable in CSMTPBodyPart called m_bQuotedPrintable to bypass the QuotedPrintableEncode function in cases that we don't want that kind of correction. Again thanks to Manuel Gustavo Saraiva for this fix.

v2.12 (25 June 2001)

• Code now links in Winsock and RPCRT40 automatically. This avoids client code having to specify it in their linker settings. Thanks to Malte and Phillip for spotting this issue.
• Updated sample code in documentation. Thanks to Phillip for spotting this.
• Improved the code in CSMTPBodyPart::SetText to ensure lines are correctly wrapped. Thanks to Thomas Moser for this fix.

v2.11 (17 June 2001)

• Fixed a bug in CSMTPMessage::HeaderEncode where spaces were not being interpreted correctly. Thanks to Jim Alberico for spotting this.
• Fixed 2 issues with ReadResponse both having to do with multi-line responses. Thanks to Chris Hanson for this update.

v2.1 (14 May 2001)

• Charset now defaults to ISO 8859-1 instead of us-ascii
• Removed a number of unreferenced variables from the sample app.
• Headers are now encoded if they contain non ascii characters.
• Fixed a bug in getLine, Thanks to Lev Evert for spotting this one.
• Made the charset value a member of the message class instead of the connection class
• Sample app now fully supports specifying the charset of the message
• Added a AddMultipleAttachments method to CSMTPMessage
• Attachments can now be copied to each other via new methods in CSMTPAttachment
• Message class now contains copies of the attachments instead of pointers to them
• Sample app now allows multiple attachments to be added
• Removed an unnecessary assert in QuotedPrintableEncode
• Added a Mime flag to the CSMTPMessage class which allows you to decide whether or not a message should be sent as MIME. Note that if you have attachments, then mime is assumed.
• CSMTPAttachment class has now become CSMTPBodyPart in anticipation of full support for MIME and MHTML email support
• Updated copyright message in source code and documentation
• Fixed a bug in GetHeader related to _tsetlocale usage. Thanks to Sean McKinnon for spotting this problem.
• Fixed a bug in SendLines when sending small attachments. Thanks to Deng Tao for spotting this problem.
• Removed the need for SendLines function entirely.
• Now fully supports HTML email (aka MHTML)

v2.04 (28 December 2000)

• Removed an unused variable from ConnectESMTP.
• Allowed the hostname as sent in the HELO command to be specified at run time in addition to using the hostname of the client machine
• Fixed a problem where high ASCII characters were not being properly encoded in the quoted-printable version of the body sent.
• Added support for user definable charset's for the message body.
• Mime boundaries are now always sent irrespective of whether attachments are included or not. This is required as the body is using quoted-printable.
• Fixed a bug in sendLines which was causing small message bodies to be sent incorrectly
• Now fully supports custom headers in the SMTP message
• Fixed a copy and paste bug where the default port for the SMTP socket class was 110.
• You can now specify the address on which the socket is bound. This enables the programmer to decide on which NIC data should be sent from. This is especially useful on a machine with multiple IP addresses.
• Addition of functions in the SMTP connection class to auto dial and auto disconnect to the Internet if you so desire.
• Sample app has been improved to allow Auto Dial and binding to IP addresses to be configured.
• Thanks go to Yaroslav Liapkov, Josef Hampl, Duncan Strand, Fritz Roland "Nick" Bjorklund, Lev Elbert and Perry Rapp for finding these problems and/or suggesting the improvements.

v2.03 (5 September 2000)

• Added a CSMTP_NORSA preprocessor macro to allow the CPJNSMTPConnection code to be compiled without the dependence on the RSA code.

v2.02 (30 July 2000)

• Fixed a bug in AuthLogin which was transmitting the username and password with an extra "=" which was causing the login to failure. Thanks to Victor Vogelpoel for finding this.

v2.01 (10 July 2000)

• Fixed a problem with sending attachments > 1K in size.
• Changed the parameters to CPJNSMTPConnection::Connect

v2.0 (21 June 2000)

• Now includes a number of files missing from the zip file.
• Updated the version number to v2 to reflect the major changes which occurred in v1.41

v1.41 (20 June 2000)

• Removed the base64 encoder from this file
• Added the base64 encoder/decoder implementation in a separate file. This was done because base64 decoding was not part of the previous implementation
• Added support for ESMTP connection. The class now attempts to authenticate the user on the ESMTP server using the username and passwords supplied. For this connect now takes the username and passwords as parameters. These can be null in which case ESMTP authentication is not attempted
• This class can now handle AUTH LOGIN and AUTH LOGIN PLAIN authentication schemes 
• Added the files md5.* containing the MD5 digest generation code after modifications so that it compiles with VC++ 6
• Added the CRAM-MD5 login procedure.
• Please note that all the support for SMTP authentication was added by Puneet Pawaia to which I am gratefully appreciated for all the hard work put in.

v1.40 (7 May 2000)

• Addition of some ASSERT's in CSMTPSocket::Connect.

v1.39 (28 March 2000)

• Set the release mode timeout to be 10 seconds. 2 seconds was causing problems for slow dial up networking connections.

v1.38 (26 March 2000)

• Updated the sample app provided with the code to be a mini mail client. This should now also give a better idea of what the code can be used for.

v1.37 (19 March 2000)

• Fixed a problem in GetHeader on Non-English Windows machines
• Now ships with a VC 5 workspace. I accidentally shipped a VC 6 version in one of the previous versions of the code.
• Fixed a number of UNICODE problems
• Updated the sample app to deliberately assert before connecting to the author's SMTP server.

v1.36 (16 February 2000)

• Fixed another compiler problem when compiled with VC 6.

v1.35 (5 October 1999)

• Fixed 2 level 4 warnings when compiled using VC 6.

v1.34 (10 September 1999)

• Improved CSMTPMessage::GetHeader to include mime field even when no attachments are included.

v1.33 (14 May 1999)

• Updated documentation to refer to RFC 822.
• Fixed a bug with the way the code generates time zone fields in the Date headers. Thanks to Randy A. Scott for reporting this bug. 

v1.32 (25 March 1999)

• Now sleeps for 250 ms instead of yielding the time slice. This helps reduce CPU usage when waiting for data to arrive in the socket.

v1.31 (22 February 1999)

• Added a Get and SetTitle method which allows a files attachment title to be different that the original filename.
• Updated sample app to include a more descriptive subject line.
• Default timeout for the code when a debug build is built has now been set to 60 seconds.
• Improved the reading of responses back from the server by implementing a growable receive buffer.
• Updated instructions on how the relevant RFC documents can be retrieved.

8 November 1998

Philip K Chung has taken the CPJNSMTPConnection class and developed a version which has the following features, The code can be downloaded here. I would ask you to forward any queries relating to this code to Philip as I am only hosting the code as a favor to him as he does not maintain a web site of his own

• no more MFC
• all collection classes and string classes from STL
• attempted to make it thread safe by making it essentially free-threaded (i.e. it should be able to handle multiple threads entering its code at the same time
• broke it out into separate modules and added a precompiled header to speed up compiling
• turned the whole thing into a DLL with a SINGLE entry point, i.e. see the public header file
• changed the directory structure around. public header file is under .../common/include and resultant DLL gets copied over to .../common/bin
• added support for CC and BCC

v1.21 (12 September 1998)

• Removed a couple of unreferenced variable compiler warnings discovered when the class was compiled on Visual C++ 6.0.
• Fixed a major bug which was causing an ASSERT when the CSMTPAttachment destructor was being called in the InitInstance of the sample app. This was inadvertently introduced for the 1.2 release. The fix is to revert fix 2) as done for v1.2. This new fix will also help to reduce the number of attachment images kept in memory at one time.
• Fixed a few errors in the help file.

v1.2 (11 August 1998)

• VC 5 project file is now provided
• Attachment array which the message class contains now uses references instead of pointers.
• Now uses Sleep(0) to yield our time slice instead of Sleep(100), this is the preferred way of writing polling style code in Win32 without severely impacting performance.
• All Trace statements now display the value as returned from GetLastError
• A number of extra asserts have been added
• A AddMultipleRecipients function has been added which supports added a number of recipients at one time from a single string. Thanks go to Bob Yang for suggested the function and providing code.
• Extra trace statements have been added to help in debugging

v1.12 (27 June 1998)

• The case where a line begins with a "." but contains other text is now also catered for. See RFC821, Section 4.5.2 for further details.
• m_sBody in CSMTPMessage has now been made protected. Client applications now should call AddBody instead. This ensures that FixSingleDot is only called once even if the same message is sent a number of times.
• Fixed a number of problems with how the MIME boundaries were defined and sent.
• Got rid of an unreferenced formal parameter compiler warning when doing a release build.
• Thanks to Chris Davidson for the all the suggestions and bug fixes.

v1.11 (18 June 1998)

• Fixed a memory overwrite problem which was occurring with the buffer used for encoding base64 attachments.

v1.1 (17 June 1998)

• Fixed the case where a single dot occurs on its own in the body of a message
• Classes now supports an optional "Reply-To" Header Field
• Classes now fully supports file attachments
• Some rework on the contents of the help file

v1.0 (26 May 1998)

• Initial public release.

v1.3 (18 January 1998)

• Full support has now been added for CC (Carbon Copy) & BCC (Blind Carbon Copy).