Call me old fashioned, but I still use sendmail. Yeah, I know there are lots of more modern and easy to use MTA's out there but I don't have the time to learn them right now. Sometimes best to stick with what you know. Anyhow...
I was wondering how to change the greeting message on an smtp connection and a long search through my O'Reilly sendmail 3rd Edition provided the answer. The following is an mc configuration for versions 8.7 or above:
Where "message" is a string that must at least contain the localhost name. By default message would be:
$j Sendmail $v/$Z; $b
In sendmail.cf which results in something like:
220 mailhost.mydomain.com ESMTP Sendmail 8.13.6/8.13.6; Thu, 1 Jun 2006 23:19:51 +0100
$j = fully qualified hostname
$v = sendmail version
$Z = configuration file version
$b = current date and time
I placed this new definition in my sendmail.mc:
define(`confSMTP_LOGIN_MSG',`$j MTA ready and waiting ; $b')
220 mailhost.mydomain.com ESMTP MTA ready and waiting ; Fri, 2 Jun 2006 00:06:08 +0100
Why did I do this? Well it's usually better with sendmail (or indeed any MTA or service) to hide the version from the outside world as this can make it a little harder to exploit.