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Postfix Archives: Re: Slow downstream site wedged my Postfix...

Re: Slow downstream site wedged my Postfix...

Subject: Re: Slow downstream site wedged my Postfix...
From: Wietse Venema (wietseporcupine.org)
Date: Fri Jan 28 2000 - 06:58:08 CST

Andrew McNamara:
> >As the count exceeds some threshold, Postfix inserts delays into
> >the the SMTP dialog, so it still accepts mail, just a bit slower.
> >If lots of mail comes in over a few connections this strategy
> >effectively slows down the sender and does not affect other inbound
> >mail too much. If the mail flood comes from all over the network,
> >eventually the connect() queue in the kernel will fill up and client
> >connections will start to time out. That's still better than Postfix
> >becoming clogged up.
>
> I was thinking about this again the other day, and it occured to me
> that it would result in all the available smtpd's tarpitting sessions
> with mail to slow sites while mail for fast sites miss out, which was

The delays are the same for everyone.

The delays simply simulate disk I/O delays that would slow
down any monolithic mailer, and give the Postfix SMTP clients
a change to deliver some mail.

        Wietse

This archive was generated by hypermail 2b27 : Fri Jan 28 2000 - 06:59:32 CST