IMail - RFC 1123 Issues

Question/Problem: Here are some questions and answers pertaining to IMail.

Answer/Solution: RFC 1123 states that you don't have to actually look up the user specified in the VRFY command. You can simply return a 252 response.   This is what IMail does when you disable the VRFY command.

An interesting statement in RFC 1123 is, "The HELO receiver MAY verify that the HELO parameter really corresponds to the IP address of the sender. However, the receiver MUST NOT refuse to accept a message, even if the sender's HELO command fails verification." That is an area that major mail systems on the internet (like AOL) continue to violate.

Also, to remain compliant with RFC 1123, you MUST have a "postmaster" account (or alias) on every domain and you MUST accept messages from null From addresses (<>). If you use the SMTP Security option, "Refuse Mail from NULL <> Senders" you will fail RFC 1123 compliance.

The RFC's specifically state if you can't deliver a message that has a NULL From, then you are allowed to trash it.  RFC 1123 says that any host MUST accept mail with NULL as the From address.

Why do we allow you to be non-compliant with the "Refuse Mail from NULL <> Senders" option? Our customers demanded that we add that option.