Hi all, We are running Exchange 2007 SP2 on Windows 2003 servers. We cannot send to one of our clients. In the queue viewer it shows "421 4.4.0 REmote server response was not RFC conformant" in the Last Error column. This is the first time this a has come up and this particular client is the only one this happens to. I saw in a related thread that it might have to do with what the mail server presents itself with in the send connector. We set it so our mail server uses it's FQDN in the send connector. When you do a reverse lookup on our mail servers IP it shows it's FQDN and our internal AD name. Any help is appreciated.

On Fri, 25-Sep-09 12:18:24 GMT, supersonic_oasis wrote:d connector. When you do a reverse lookup on our mail servers IP it shows it's FQDN and our internal AD name. Any help is appreciated. What was the response that isn't RFC comformant? Check your SMTPprotocol log file.I'm going to guess that it's either HELO or EHLO, and that the nameyou send in that command doesn't match the name in the PTR record foryour IP address. If it's not that it's probably something close to it.I'm not sure what your meant when you said "When you do a reverselookup on our mail servers IP it shows it's FQDN and our internal ADname". The PTR record should contain the FQDN. The FQDN should be ableto be resolved from the Internet. If the FQDN uses your internaldomain name and there's no external DNS for that domain then that maybe your problem. The solution, then, is to configure the machine touse the FQDN that uses your external domain.---Rich MatheisenMCSE+I, Exchange MVP--- Rich Matheisen MCSE+I, Exchange MVP