Wietse:
> My conclusion is that Postfix can continue to provide basic policies
> that avoid worst-case failure modes, but the choice of the settings
> that control those policies is better left to the operator. If the
> receiver slams on the brakes, then Postfix can suspend deliveries,
> but the sender operator will have to adjust the sending rate.
Rafael Azevedo - IAGENTE:
> I agree with Reindl, I guess Witsie is now better understanding
> the problem here.
Please take the effort to spell my name correctly.
When a site sends a small volume of mail, the existing Postfix
strategy is sufficient (skip a site after N connect/handshake errors,
don't treat a post-handshake error as a "stay away" signal). The
email will eventually get through.
When a site sends a large volume of mail to a rate-limited destination,
'we" believe that a stragegy based on a bursty send-suspend cycle
will perform worse than a strategy based on an uninterrupted flow.
Why does this difference matter? Once the sending rate drops under
rate at which mail enters the mail queue, all strategies become
equivalent to throwing away mail.
This is why bulk mailers should use a strategy based on an uninterrupted
flow, instead of relying on a bursty send-suspend cycle.
This is consistent with my conclusion cited above. The sole benefit
of adding the switch is that when it trips, the operator knows they
need a different sending strategy (reduce rates, snowshoe, whatever).
Wietse
