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Home » Kerio User Forums » Kerio Connect » Mail sent but still in Queue (Mail sends and gets received but still re-sends)
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GazzaBot

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Hi,

We have a customer with a Connect mailserver that are experiencing regular problems sending repeat mail messages.

It seems to be more specific to messages with attachments. The message enters the queue, processes to 100% then returns to the queue with error 'Connection Lost'.

In most cases the recipient does receive the mail and often multiple times.

In my logic it would seem that before the server has received a received confirmation it times out and restries.

This has been going on for a wuhile now and they are getting more anxious to resolve this issue.

Please help, all suggestions welcome.

Many Thanks
G

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Pavel Dobry (Kerio)

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SMTP client in Kerio Connect is using 2 minutes timeout when sending the message out. If the receiving server holds the message in some anti-spam/anti-virus for some time without accepting it then the client hits the tiemout and tries to send the message again. We are going to make the timeout more flexible in some future versions.
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GazzaBot

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Is there no possible registry or other backgraound setting we can edit to change this setting manually?
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TorW

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I had the same problem at a customer site a few years ago (although not with Kerio). Even though the queue processor happily sent the mails on their way, their internet connection had so much packet loss and so low bandwidth that the other end's final acknowledgment came after the timeout threshold. Lather, rinse, repeat.

Fiddling with the timeout value will only get you so far. The real problem is probably somwehere else.
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GazzaBot

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Thanks TorW. We have got the ISP investigating line problems but we just figured that if we could increase the timeout it would help keep the message from re-entering the queue.
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GazzaBot

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We have done some line testing and the line is a 4Mb line with upload restricted to 512Kbps. From what we can tell a message with a 5MB or bigger attachment processes to 100% in the queue, then waits and finally goes back to be re-processed. Could Antivirus checking along the route to the recipient be causing the 2 minute timeout restriction to be reached? If so, we need to know when this timeout is going to be able to be flexible.

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TorW

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Is this only happening for a specific receiving domain? Also check if you have a Cisco router somewehere doing "SMTP inspection" or similar. Some Cisco routers have a known issue with it, creating all sorts of mysterious timeouts. Google for "Cisco SMTP inspection", read the results and weep ...
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GazzaBot

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It is random domains, seems more related to attachment size than domain. There is a Fortigate firewall device connected to the router, not sure if it could also have those mystery timeouts as you mentioned above.
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freakinvibe

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Fortigate is known for timing out SMTP. Try to switch off SMTP inspection:

http://forum.mailenable.com/viewtopic.php?f=7&t=17210

Dexion AG - The Blackberry Specialists in Switzerland
https://dexionag.ch
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GazzaBot

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Thanks for all the reponses. We have managed to get the ppl managing the Fortigate to disable SMTP checks on outgoing and so far things seem good. Will only really know within a week or two.
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