On Tue, Jan 08, 2013 at 01:59:14PM -0200, Rafael Azevedo - IAGENTE wrote:
> But Witse, would you agree with me that error 4XX is (in general
> cases) a temporary error?
It is a temporary error for *that* recipient. It is not a global
indication that the site is temporary unreachable. Nor is there
any indication how long one should wait, nor that waiting will make
things any better.
Generally, delaying deliver *increases* congestion, since more mail
arrives in the mean-time, and once delivery resumes the volume is
even higher.
> Why keep trying when we have a clear signal of a temporary error?
Postfix does not "keep trying", it defers the message in question
and moves on to the next one. Your mental model of email queue
management is too naive.
This is a very difficult problem, and there is no simple answer.
> Also, if we had a temporary error control (number of deferred
> messages by recipient), it would be easy to identify when postfix
> should stop trying at least for a while.
Given an arrival rate of ~50k msgs/day, you need to send at least
1 msg/sec to avoid growing an infinitely large queue. This is basic
arithmetic. Gowing slower does not work, your queue grows without
bound.
Let the recipients know that if they want to continue to receive
your email they should choose a new provider that is willing to
work with legitimate senders to resolve mail delivery issues. Then
stop sending them email.
--
Viktor.
