Auteur: Andrew Johnson Date: À: exim-users, 'Daniel Tiefnig' Sujet: Re: [exim] Extremely Simple(?) greylisting with exim?
>> Does it make sense to deliver to the 2nd MX if we know the 1st MX does >> not accept mail for the address? >You can certainly argue that it does not, because in a classical configuration, the 2nd MX is just going to forward the >message to the first.
However, one of the reasons people have a secondary MX is so that they can
still take ownership of a message even if it could not be delivered to it's
final destination.
Also, take this scenario, what if the company hosts both MX's, they put a
second there incase the first server drops dead, or indeed they could have
the same MX weighting for load balancing. Both these servers sit in their
DMZ and both then forward the emails to an internal server for user
delivery. In this case, it would be important to deliver to the secondary MX
even if the fist turned it away.
This of course assumes a temporary error, if a 5xx error is received from
either MX, game over.