Hi all,

Is there a way to limit the number of outgoing filtered emails connections to final SMTP server ? I explain : if the final SMTP server is down for a long time, when this server comes up, spamfilter send a very large number of connections regarding what it's stocked in it's queue... In my case, I got over 1000 tcp connections at the same time, and the final smtp is, in this case, very busy.

Thank you for reply.

Hi web123,

Thank you for reply; I have tested, it's not the case (for my example, max incoming 50 connections), more than 500 with lot of emails in queue...

Dear Roberto,

I agree with this parameter, but when the end smtp server is not available for a long time, I assured you this limit (twice from input) is broken (for my case : 100 max connections in with spamfilter, so never more than 200 connections max to my end server, but when my end server crashed, with more than 4000 emails waiting in spamfilter's queue after the crash, I had more than 600 connections on my end server). To add, spamfilter flush is parameted with 15 minutes retry. If in the lap of time of 15 minutes the 200 connections are still working, is there a way that spamfilter reallow more connections ? Is there another parameter something else to limit ?
I have try to add between spamfilter and smtp end server iptable rule with a max_ip_connection to 300. Iptables dropped connections during the tranferts of spamfilter's queue to end server. So spamfilter in my case done more than twice input connections.
Thank you for help !

If SpamFilter has 100 max incoming connections, the outgoing connections to your server should only be 50. If you see a higher number, right now we're thinking this could be caused by your relatively short flush interval. It's possible (we'll be checking shortly) that SpamFilter applies the outgoing limit for each time the queue is being flushed. If a pre-existing flush is in process, SpamFilter may perform another one after 15 minutes, adding another 50 connections to the existing ones. So after an hour, if your mail server is slow in accepting the incoming mail flow from SpamFilter, you could potentially have 4 concurrent flushes, each with 50 connections, thus adding to 200.
If this is the case, restoring the interval to the default of 60 minutes or higher wold mitigate the problem.
As a side-note, processing 4,000 emails should not take a long time, they should be delivered in a few minutes, depending on the efficiency of the email server and its hardware. Have you checked SpamFilter's activity logfiles (and/or your mail server's), to see if there are any other issues causing the slowdown?