[dspam-users] mx records for dspam relay

So, I'm working out some ideas to move our dspam implementation from
running locally on the mail server to a relay server. So far, the
idea is to set mx records for the names which mail is sent to, like
@dtcc.edu, to point to mx.dtcc.edu. The mx.dtcc.edu server would run
dspam and clamav which I was going to setup using the relay.txt
file. The mx.dtcc.edu server would have dspam send the mail to the
real mail server using smtp settings in the dspam.conf file.

The part I'm getting held up on is a backup mx server. I really
would like to use a backup mx. I would like mail to queue up on that
and then relay it to mx.dtcc.edu. But, what will prevent those
queued messages from not getting delivered directly to the real
server without going to mx.dtcc.edu first?

Some people still receive mail using the mail servers real hostname.
I can set mx records for that hostname pointing to mx.dtcc.edu and
backupmx.dtcc.edu (or some other name). If mx.dtcc.edu is down for a
couple minutes and mail is accepted at backupmx and queued, would the
mail then get sent to mx.dtcc.edu when it comes backup? Would it see
the real mail servers hostname in the To: field and try to deliver
there since the primary mx is down?

I'm hoping I can just configure the dspam relay box as the primary mx
for all of the domains and hostnames, then configure the secondary mx
to queue messages. I hope the secondary mx will just wait for the
primary to come online and send everything that way.

The other thing I was thinking about was using the InnoDB format for
MySQL. Since there is no free hot backup tool and my boss was a
little upset when I asked about buying the commercial one, I was
thinking about shutting down postfix and mysql to run a backup. Then
bring it back online when the backup was complete. While it's
offline, I'd rather have a secondary mx queuing messages. If people
start getting temporary failure bounce messages, we will most likely
get some complaints.

Another concern would be mail that is sent locally from the mail
server itself. If I were running pine and sent an email to a local
user, is sendmail or postfix going to be smart enough to send the
message to the relay box or will it deliver locally (thus bypassing
dspam). I'm not as worried about this situation since all the local
users are admins and they aren't sending spam.

Anyone care to share some best practices when it comes to mail relays?

Thanks,

Pat

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Pat Hennessy, RHCE                        (path@dtcc.edu)
Senior Systems Specialist
Systems, Stanton/Wilmington Campus
Delaware Technical and Community College
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