Protocol Standards

There are several core standards which form the foundation for sending and receiving email messages over the Internet and corporate intranets. These standards are defined in documents called RFCs (Request For Comments) which describe how the various protocols should be implemented. The following standards were used when implementing the email related controls in the SocketTools ActiveX Edition:

RFC 822 documents the basic structure of email messages, including how messages should be formatted and what the standard message header fields are. RFC 2045 documents Multipurpose Internet Mail Extensions (MIME), which details how more complicated messages are structured. File attachments, HTML formatted messages and other more complex aspects of message composition are covered by the MIME standard. The Internet Mail control supports both RFC 822 and MIME formatted email messages, including multipart messages which contain alternate text and file attachments.

RFC 1939 documents the Post Office Protocol v3 (POP3) which is used to retrieve messages from a user's mailbox on a server. The Internet Mail control uses this protocol to enable applications to list, retrieve and delete messages.

RFC 3501 documents the Internet Message Access Protocol v4 (IMAP4) which is used to manage information in a user's mailbox on the server. Unlike the Post Office Protocol, where messages are downloaded and processed on the local system, the messages on an IMAP4 server are retained on the server and processed remotely. This is ideal for users who need access to a centralized store of messages or have limited bandwidth.

RFC 821 documents the Simple Mail Transfer Protocol (SMTP) which is used to deliver messages to one or more recipients. RFC 1869 documents extensions to the protocol which provide additional services such as delivery status notification and authentication. The Internet Mail control implements both the standard and extended SMTP protocols.