>Sorry, the day got pretty crazy and I must have missed that message. I guess
>I don't understand why the official host name must be a fqdn, is it a
>requirement of the internet mail standards? Does it just have to be in the
>format: domain.com or does it have to be a registered name?
IMail uses it for several purposes, such as on the greeting (what you first
see when you telnet to port 25 on your mail server), and in the HELO/EHLO
text. The RFCs require this to be a fully qualified domain name. That's
just the way it is. It can't be an IP address or just "machinename" or
whatever.
You aren't supposed to use an unregistered domain name, but you likely
could get away with it. But why would you want to?
>Do recving email servers do a reverse lookup on the sever name to filter
>out spam?
They may test the HELO/EHLO domain, but it's unlikely. Probably 80% of
E-mail clients are misconfigured and send out just a machine name, or
something like "localhost". So the spam testing would need to determine
whether the mail was incoming or outgoing first (if it is incoming, it
would test it, since it should have been sent by a mail server, not an
E-mail client).
Less likely would be filtering on the domain listed in the greeting. All
IMail servers would fail that test, since IMail reports the domain as
"X1". So it wouldn't matter what you used as your host name.
But, the fact remains, you're expected to follow the rules. There may not
be much of a penalty (if any) today, but it's quite possible that as spam
gets worse, people will get stricter and not accept mail from poorly set up
mail servers. In the past 24 hours, we've encountered mail servers without
"abuse" addresses (not required, but really should be there), with no
"postmaster" address (which is required), that wouldn't accept bounce
messages (which is required), which don't record the IP address of the
sender (not required, but necessary for tracking spam), and an invisible
mail server (it reported itself as "localhost@localdomain", which is
illegal, and had no reverse DNS entry, which is technically illegal as
well, and hard-to-find Whois data).
>Our network security policy requires the mail server to be behind a
>firewall. Is this going to be a problem, and why?
That's not a problem, just so long as the firewall doesn't do anything it
shouldn't. If it blocks port 25 access or blocks access to the mail server
in any other way, it would be a problem. Or, if it mucks with the SMTP
protocol (as we've seen here recently, blocking EHLO and blocking some
data), it would be a problem.
> or is it just that the firewall has to support ESMTP?
No, the firewall doesn't need to support any mail commands. The problem
firewalls are the ones that BLOCK ESMTP.
>Does ESMTP require a different port than 25 to send and recv SMTP AUTH
>commands?
No. ESMTP is just an enhancement to SMTP, and is all done on port 25.
-Scott
Declude: Anti-spam and Anti-virus solutions for IMail. http://www.declude.com
Please visit http://www.ipswitch.com/support/mailing-lists.html
to be removed from this list.
An Archive of this list is available at:
http://www.mail-archive.com/imail_forum%40list.ipswitch.com/
