The IMTA is fully compliant with RFC 822 and with RFCs 1521 and 1522 (MIME), the standards for the formatting of Internet text messages. SMTP support complies with RFC 821 (Simple Mail Transfer Protocol) and RFCs 1425, 1426, and 1427 (SMTP extensions). It also complies with various other Internet formats and protocols, including RFC 1623 (Internet host application requirements), RFC 1090 (SMTP on X.25), and RFC 976 (UUCP mail interchange).
See Appendix A, "Supported Standards" for a list of all of the standards supported in SIMS.