[Mimedefang] Slightly OT: Advice on updating MX record (was SMTP error return after DATA?)

Michael Sims michaels at crye-leike.com
Fri May 9 15:20:02 EDT 2003


Sorry to post something that isn't directly related to MIMEDefang, but since
I got so much good advice related to my load problems I thought I'd ask a
quick question.

I'm trying to decide exactly how I want to switch the MX record for my
domain over to my new dedicated MD/SA server.  My current MX will still have
to listen for SMTP connections on the public internet because I have some
satellite offices that have their own internet connection and are not using
VPN to get to our network.  It's no problem though, they have static IPs and
I can easily control who can connect via an access map.  BUT, I'm concerned
about the amount of time it will take for my DNS change to propagate out to
the rest of the net.  I've read that most see changes in 12-24 hours, a good
bit in 48 hours, and some may take as long as 72+.  If I just switch my MX
in one fell swoop then sites that haven't received the update will still be
trying to relay mail to my old MX record and their connections will be
rejected.  If it takes them a while to get the updated DNS information they
may start bouncing mail destined for my domain.

So, I was thinking about getting the new server up and running it in
parallel at first, and adding it as a secondary MX record with a lower
preference.  I could then wait for that change to propagate out, then switch
over to the new setup with the new server as the sole MX record.  That way
sites that are slow to update DNS should theoretically fall back to the
secondary MX when the first one rejects their connection.

Does this sound reasonable, or am I making it too complicated?  I'd
appreciate any advice...

___________________________________________
Michael Sims
Project Analyst - Information Technology
Crye-Leike Realtors
Office: (901)758-5648  Pager: (901)769-3722
___________________________________________




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