maillscanner/postfix saturates bandwidth :-(

Harondel J. Sibble mailscanner at
Wed Oct 10 00:21:12 IST 2012

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
Creating Solutions for the small and medium business computer user.
help at (use pgp keyid 0x3AD5C11D)
(604) 739-3709 (voice)

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