SquirrelMail "talks" several protocols. To make sure that we are standards-compatible, we need to refer to RFC documents. Here's a list of the ones we use a lot: They are available from a wide variety of places on the net. For instance, if you want RFC 822, you can jump directly to it at http://www.faqs.org/rfcs/rfc822.html http://www.rfc-editor.org/rfc/rfc822.txt http://www.imc.org/Searchable/rfc822 NUMBER DESCRIPTION ----------------------------------------------------------- RFC 1730 IMAP version 4 RFC 2060 IMAP version 4rev1 RFC 2183 Content-Disposition MIME header RFC 2298 Details return receipts RFC 2342 The IMAP4 NAMESPACE command RFC 2616 HTTP/1.1 RFC 2683 IMAP4 Implementation Recommendations RFC 2822 Format of an email message (sendmail)