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Limiting outgoing filtered emails ?

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    Posted: 13 January 2009 at 1:20pm
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.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Web123 Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2009 at 1:24pm
I think outgoing connections should be half of what you have for max incoming connections!
/Kim
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shade Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2009 at 1:31pm
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...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 13 January 2009 at 4:46pm
Shade,

Kim is correct. SpamFilter will use a number of concurrent outgoing connections equal to 1/2 the "Max concurrent incoming SMTP connections". Please note that this is not the setting relative to the max connections from the same IP, but the setting just above that one the GUI.
Roberto Franceschetti

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shade Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2009 at 4:19am
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 ! Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shade Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2009 at 10:04am
To add, for the moment, I have resolved the problem by adding a third software solution limiting connections between spamfilter and the end smtp server.

To finish with the rules twice output connection from input connection rate parameter, for my personal case, I have some time about 50-60 connections at the same time, about 10 max are real email, other spam reject by spamfilter. So, If I put MaxInboundConnections=50, all other connections are reject (good or spam emails) and spamfilter can make about 100 connections to my end smtp server, so I need to put MaxInboundConnections=100, spamfilter can make as 200 connections to my end smtp server, but in many case (except after a crash from end smtp server) there is never more than 5-10 connections at the same time, all other being stopped by spamfilter. It is also for that case I think another "MaxOutboundConnections" will be great.

Regards.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 14 January 2009 at 5:22pm
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?
Roberto Franceschetti

LogSat Software

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shade Quote  Post ReplyReply Direct Link To This Post Posted: 15 January 2009 at 2:06am
Dear Roberto,

All is working for now (rising flush time, limiting connections).

Thank you ! Wink
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