>But it appears that the RFC allows it (I must be missing >something!)...This is what the RFC says:
yes, you are missing that a domain literal is [A.B.C.D], not A.B.C.D which is what spammers send. > These commands are used to identify the SMTP client to the SMTP > server. The argument field contains the fully-qualified domain >name > of the SMTP client if one is available. In situations in which the > SMTP client system does not have a meaningful domain name (e.g., >when > its address is dynamically allocated it's subcriber net, and we refuse it anyway, > and no reverse mapping record >is no PTR is another infraction that we prefer to reject. > 4.1.3), optionally followed by information that will help to >identify > the client system. I don't remember seeing any "information" following these naked HELO ip.ad.rs.ss > by dots and enclosed by brackets such as [123.255.37.2] "enclosed by brackets" I don't see, and I bet postfix when logging these HELO's doesn't strip the [], either. Len
