WARNING: One or more of your mailservers is claiming to be a host other than what it really is (the SMTP greeting should be a 3-digit code, followed by a space or a dash, then the host name). If your mailserver sends out E-mail using this domain in its EHLO or HELO, your E-mail might get blocked by anti-spam software. This is also a technical violation of RFC821 4.3 (and RFC2821 4.3.1). Note that the hostname given in the SMTP greeting should have an A record pointing back to the same server. Note that this one test may use a cached DNS record.
I used to get these on my last server. The tech I had asked from the company then said it was not a big deal. However I’m not sure how spam tests fully work. I read something briefly about mail in general though that might help… I’ll see if I can find it…
A few servers reject messages from clients whose HELO parameters do not match the results of PTR lookups on their IP addresses. This behavior is a disaster in practice; surveys in 1998 found that more than 10% of all clients by volume use invalid HELO parameters.
…from the SMTP/HELO page.
The way I’ve chosen to build servers now is put the hostname on its own IP and route each domain’s mail.domain.com record on the server to that one IP. Gets rid of the warning. But then I have the mail server listening on every other IP when its not needed. Hence my previous post in this forum, still trying to get to the bottom of that.
