[Gllug] Rejecting mail at backup MX

Jason Clifford jason at ukpost.com
Tue Feb 10 14:15:37 UTC 2004

On Tue, 10 Feb 2004, Bruce Richardson wrote:

> No, that isn't the purpose of a backup MX.  It's one of the functions
> but not the only one.  It is entirely possible for there to be a
> situation where arbitrary e-mail box A cannot connect to B's primary but
> can route to B's secondary even though B's primary is up and running and
> perfectly visible to the secondary.  I see this happen every day.

Yes this can happen but it's rare.

> Furthermore, spammers and viruses often deliberately target secondaries,
> trying to bypass the defensive features on the primary.  The
> call-forward feature prevents them from succeeding.

Yes but it's more complicated than duplicating the maps and may introduce 
excessive latency in a connection.

> Secondly, I clearly stated that it can be configured to allow the
> messages through when the end system is not availab.e

Which is precisely what the OP was seeking to avoid.

There isn't a single "right" answer to this issue. The call forward 
mechanism you are using is one good way or dealing with some of the issues 
arising from backup MX abuse. I don't think it's necessarily the right one 
for the OP though.

Jason Clifford
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