SMTP Service Causing High Internet Usage

Posted on 2011-03-22
Last Modified: 2012-05-11
Customer is complaining that the Internet is very slow.  After some troubleshooting, I have determined that SMTP is causing the issue.  The server is an SBS2003 running Exchange.  When pinging with the SMTP service started, the reply is 3000-4000ms.  When stoping the SMTP service, the ping reply drops down to a reasonable 20-40ms.  I checked the queue in System Manager but it is empty.  Any ideas?
Question by:ptsolutionsinc
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Expert Comment

ID: 35192155
is the SMTP Service actualy passing any traffic out the internet connection or is it slowing a proxy used for internet access by usisng CPU and memory if its the first option i would put a sniffer on the connection and see what is being sent second option try re-service packing exchange

Author Comment

ID: 35192215
we dont have a proxy and and CPU usage is normal.  how do i put a sniffer on the connection?
LVL 31

Expert Comment

ID: 35192469
It may be receiving a large message/s and you won't see that in the queue.

What are the message size limits? Hopefully 5Mb max 20Mb...

You can turn on SMTP protocol logging to see what is happening, but I would recommend setting message size limits if you have none.
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Author Comment

ID: 35193465
I have checked the message size limits and they were set to unlimited.  i changed to 20MB but the issue continues.  I followed Microsoft's Knowledgebase to enable SMTP protocol logging and MSExchangeTransport is already set to Maximum but the knowledgebase does not show how to access the logging.  where do I go to check this?
LVL 31

Expert Comment

ID: 35194891
Should be under c:\windows\logfiles

Did you restart SMTP after setting the size limits?

Accepted Solution

ptsolutionsinc earned 0 total points
ID: 35195132
Yes, I did restart the SMTP service.  The c:\windows\logfiles folder does not exist.  I did however research other Experts-Exchange posts and found a post that helped me resolve the problem.  Not sure if there is a way to link this post to that post but the post is below.  The accepted solution is what helped me out.


If you block TCP Port 25 outbound on your firewall - the message flow should stop and then you can see the messages in the queue and delete the offending ones.  Then open port 25 back up again and problem solved.

When a message is being sent - the queue will appear empty - this is nothing unusual.
LVL 31

Expert Comment

ID: 35196406
Thanks for the final solution, feel free to close the question.

Author Closing Comment

ID: 35275392
I researched other Experts-Exchange posts and found a post that helped me resolve the problem.  Not sure if there is a way to link this post to that post but the post is below.  The accepted solution is what helped me out.

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