Deferred  queue If Postfix cannot deliver a message to a recipient it is placed in the deferred queue.  The queue manager will scan the deferred queue to see it if can place mail back into the active queue.  How often this scan occurs is determined by the queue_run_delay.  Postfix will scan the incoming queue at the same time as the ...

Alternatives Program for MTAs The alternatives program is a way to change the default mail server so that it will be Postfix. This program is only necessary for CentOS not Suse or Ubuntu, as Suse and Ubuntu both use Postfix as the default. Alternatives is a program that will allow you to assess and change the mail program or MTA ...