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> Dear Colleagues,
>
> in our infrastructure we are using Postfix as a relay server which is
> responsible for transfering messages from our MS Exchange and Production
> systems. Our infrastructure include several Postfix relays:
>
> M$Exchange(lan) ---> Postfix1(middleware lan) ---> Postfix2(application
> lan) ---> Postfix3(web lan) ---> Internet
>
> I would like to ask You, what will happend if Postfix2 will be offline ?
> How Postfix1 will behave ?
As required by SMTP mail standard, Postfix will retry the email up
to some time limit (with Postfix, maximal_queue_lifetime, default 7d).
> M$ Exchange sending every minute ~10 000 E-mails.
I recommend implementing Postfix2 etc. with multiple MTAs, perhaps
behind HaProxy load balancers.
> *If outage will take longer, we need to store thousands of E-mails in the
> deffered queue, is there any limit for number of messages stored in the
> deffered queue ?*
Your math is off. With 10000 messages per minute, that is over a
million email messages queued for every two hours of downtime. You
simply cannot afford days of downtime with such a volume.
Wietse
