>There is certainly nothing there > to override the earlier RFC (which I've forgotten) that > specifies a similar recommendation but goes on to say that > the receiver MUST NOT reject the message based on an address > lookup mismatch for the HELO/EHLO name (obviously written by > someone who realized that multi-homed servers are common and > that corporate servers often live behind NAT firewalls and > don't even know the address that will be used the public side). > > -- > Les Mikesell > les at futuresource.com I believe you are referring to RFC 821: 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. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.