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Messages stuck in queue

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jerbo128 View Drop Down
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    Posted: 13 July 2007 at 11:49pm
Roberto and Crew:
 
Lately I have been seeing several messages per day stuck in the queue.   Ranges from 2-20 per day, and when I try to deliver them, shows a read timeout in the spamfilter log.  I have contacted the admin of the mailserver, and they claim it is our server causing the timeout.
 
Usually, when this happens, I will see the same message to several users in the queue.  Out of 4000 users, I only have about 10 unfiltered addresses.   I would say that 80% of the stuck messages are to "unfiltered" recipients whose messages are just being passed through.
 
This happens to only this one customer mail server.   This spamfilter server receives 60K-80K messages per day, and 90% go to this one customer.  For testing purposes, I copied the queue files to my testing server, and ran ethereal while I flushed the queue.
 
I have emailed a spamfilter log, ethereal dump, 2 messages, and a couple of ethereal exports.
 
I am running .692 Ent on a Win2003 x64 Box with 4GB RAM.  I have 25-50 concurrent connections inbound.
 
Mail server is running some flavor of Linux.  I can find out anything you need to know on it, just let me know.
 
I can get you RDP to the testing server if you would like.  Let me know if there is any other info that you need.
 
Thanks in advance,
 
Jerbo128
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Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 14 July 2007 at 11:37am
Jerbo128,

Thanks for the excellent troubleshooting you did, and all the data you gathered. You really made it very simple for us to find what is happening.
 
Please look at the filtered etherreal capture image below in this email (this won't be posted in the forum) showing traffic for one of the two emails. Notice that SpamFilter issues the MAIL FROM command at 11:04:05. It takes the remote server running Sendmail one entire minute to send back a response accepting the sender. SpamFilter has a built-in timeout that disconnects an idle connection after a minute, and thus disconnects the session.
 
Please note that both the emails you provided the disconnects occur right after the RCPT TO command and before SpamFilter sends the "RCP TO" command. The fact that the recipients are often in the unfiltered list should not matter here, as the email is being forwarded after being received. The fact that they are unfiltered simply means that it will be very likely that the email is spam to begin with, as otherwise SpamFilter would have blocked it :-)
 
Another thing to consider is that this email was spam. It's possible the remote Sendmail may have been doing some checking of its own on the senders (Merrill1Couch@free-craps-online-top.info and hannahjw@williams.co.uk) to see if the addresses were valid. In this case, this may explain the delay in Sendmail in sending a respose.
 
There's two settings in the SpamFilter.ini that can help here:
;Timeout when delivering emails to the destination SMTP server (in seconds)
ReadTimeoutOutgoing=60

;Force disconnect of sessions if a command has not been received within the last nn seconds
ReadTimeout=60

You may try to increase the "ReadTimeoutOutgoing" to see if that help. If the timeout still occurs after one minute, try increasing the "ReadTimeout".

Roberto Franceschetti

LogSat Software

Spam Filter ISP
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jerbo128 Quote  Post ReplyReply Direct Link To This Post Posted: 14 July 2007 at 3:50pm

Roberto

I have increased the outgoing timeout to 120 seconds and the queue was successfully delivered.  Hopefully that will be a permanent solution.

Thanks again for all of your help!

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