Exchange 2003 SMTP Queue Issue

TonyWalker821 used Ask the Experts™
After altering our SMTP Connector to use DNS instead of a Smart Host we now have 2 SMTP Queues with radomly generated queue names where all are outbound mail is sitting.  Can anyone help me resolve why this is happening as no mail is leaving the Exchange server currently.
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Sounds like an error in the routing. Normally DNS routing will create a queue to each destination SMTP server it will use and delete it when done. For some reason it sounds like your DNS routing is only sending to these 2 addresses. Do you recognise them? Spam filters? Smart hosts elsewhere perhaps?


Hi ,

I think you may be wrong with your diagnoses as there are some normal queues displayed which are empty but ALL outbound mail regardless of destination is being dropped into a queue which looks like something this.  
a_12hhgj3u4hk2jh24u3g3h24 (SMTP)

It should be dropped into a queue for each destination domain but isn't.

As I have tried to explained in the question, we were using a smart host to send our outbound mail through but have since changed this to use DNS but now all the mail that was stacked up in the smart host queue is now stuck in one of the two randomly named SMTP queues.  When we restart IIS they seem to temporarily split and create the correct SMTP Queues but after a few seconds go back into the randomly named queues.

Let me know if you have any other ideas please!

So it is creating the DNS queues for the destinations but not routing the mail into it?

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Hi I have attached a screenshot of the mail queue for you to try and help.
Looks like all DNS queues are being blocked - Note the 3 at the bottom as well which have queued mail.
Is your firewall configured to permit you to send from the Exchange server to anywhere? We set our firewall to only permit SMTP from Exchange to the Spam filter. Definitely check that. Also try restarting the MTA agent service as it may have hung on a message. Failing that you may need to delete the oldest queued message and restart the service again to kick it off. See here for how:


Combination of this suggestion and others resolved the issues.
What was it in the end?


general dns issues and router / firewall config.

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