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Re: Limiting outgoing SMTP connections when relaying message
From: Victor Duchovni <Victor.Duchovni_at_nospam>Date: Wed Mar 09 2011 - 22:29:04 GMT
To: postfix-users@postfix.org
On Wed, Mar 09, 2011 at 10:21:44PM +0000, Tim wrote:
> Victor Duchovni wrote:
>> On Wed, Mar 09, 2011 at 09:40:26PM +0000, Tim wrote:
>>> What happens is that Postfix receives the message from the sender, queues
>>> it, then immediately connects to *all* of the destination servers
>>> simultaneously and starts sending the message to them. This completely
>>> saturates the upstream Internet link, so each destination server sees a
>>> gradual trickle of data, and virtually all of them time-out while
>>> receiving data.
>> On a server with limited network capacity set a small process limit for
>> the "smtp unix ... smtp" delivery agent entry in master.cf.
>> http://www.postfix.org/master.5.html
>
> Thanks.
>
> Not sure I fully understand what effect that will have, but I've set the
> process limit to 2.
>
> Will that restrict the number of outgoing connections to 2? I'm confused.
Each delivery agent delivers one message at a time. With two delivery
agents there are at most two parallel deliveries. The default process
limit is 100. I would first try 10 or 20, before taking it all the way
down to 2. Such a small process limit can create severe congestion...
-- Viktor.