maillscanner/postfix saturates bandwidth :-(

Harondel J. Sibble mailscanner at pdscc.com
Mon Oct 22 17:43:50 IST 2012


Interestingly enough, throttling INBOUND smtp at the firewall level resolved 
this issue.  Now they have no issues with sending out large mailouts.  
<shrug>

On 9 Oct 2012 at 16:21, Harondel J. Sibble wrote:

> 
> 
> On 24 Sep 2012 at 15:09, C. Jon Larsen wrote:
> 
> > > Basically the dsl connection they share with another office was saturated
> > > when the office admin did a mailout on friday to about 2000 of their
> > > subscribers, each email was about 3.5mb total with conversion overhead.
> > > When I say saturated, I mean in both the upstream and downstream
> > > directions. According the admin who runs the multitenant network in this
> > > office, he was seeing a sustained 1.6mb/s INBOUND connection to my
> > > client's firewall while this was happening.
> 
> > > I'm trying to figure out the best way to deal witih this moving forward,
> > > is there additional throttling I need to do at the postifx level or the
> > > mailscanner level or something else.  I was also surprised as my
> > > understand of postfix is that it does connection throttling by default.
> > 
> > You can play with variations of these settings in main.conf to control how
> > much email is sent out - these go into main.conf
> > 
> > local_destination_concurrency_limit = 2
> > default_destination_concurrency_limit = 2
> > initial_destination_concurrency = 2
> > 
> > smtpd_client_connection_count_limit = 10
> > default_destination_recipient_limit = 20
> 
> I'll do some testing with these as still getting same behaviour.
> 
> Setup caching dns server on the Mailscanner box, to replicate circumstances
> similar as before, had user send from outlook via exchange an email with no
> attachments, just body text to approx 550 recipients and basically same issue
> cropped up again, I had to eventually do
> 
> postqueue -p
> 
> postsuper -d 
> 
> on the messages in the queue to get things back to normal.
> 
> Which do you figure will give best bang for the buck assuming I add one at a
> time?  Are there general rules of thumb for the various values?
-- 
Harondel J. Sibble 
Sibble Computer Consulting
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