Mail to just 1 domain does not get delivered.

[Magzy]

Hi All,

Here is an odd situation that I hope someone can help with.

Server - Exchange 2000 SP3, on good hardware with a lot of free resources.

SMTP mail configured to be routed via an SMTP connector. The connector is set to route messages via DNS, and has the default settings.

The server sends fine except to 1 domain. For that domain, it does the following:

1st Mail reaches the queue and gets sent. The queue for that domain shows up as active, even though there is no longer a message in the queue. That message is delivered OK. Subsequent messages just sit in the queue until eventually the queue goes into "retry" mode. Once this happens, you can force a connection and the above repeats. Basically it just sends out 1 message at a time.

I have checked all the usual (DNS etc) and it all appears to be OK. I can even telnet from the server console to the address of the mailserver in DNS and send a message manually and that works just fine!

Any ideas would be most gratefully received!

Thanks,

Magz...

 

[xmsre]

Sounds like you're trying to send to a smtp server that does not support multiple threads. Back in the MSMail/Exchang3 5.X days, that used to be a big issue when sending to a msmail gateway. I think the resulution was to lower the maximum number of connectons per host.

 

[Magzy]

Hi,

Yes, I thought about this but they're running Exchange 2000. I have recently discovered some more information however. They used to be able to mail this domain fine, bit recently they changed their internet link and thus the default gateway on their network. Once they did this, they started having issues mailing the domain as described above.

I don't see why this would be an issue, but if anyone else does then that'd be great!

Cheers,

Magz.

 

[mrbusy]

Its probably not this but have you considered the DNS caching time? If the mail server is resolving the MX record using DNS then it will cache that IP address temporarily and try to use that cached value until it expires.
It seems unlikely but it might be worth trying ipconfig /flushdns on the mail server to see if forcing it do another DNS lookup changes anything.

As for the default gateway, have you tried running a packet sniffer on your mail server to see what packets are actually flowing back and forth? This might give you an idea of who is at fault if you compare the first email that works with the subsequent ones that fail.

 

[vespa61]

I am having a similar problem, I have only one domain in which mail cannot be delivered to. I am going to flush the DNS cache when I the current back-up that is running is finished.

Here is the error message recieved when trying to send an email to any user at the problem domain:

Your message did not reach some or all of the intended recipients.

Subject: test
Sent: 4/12/2004 9:53 AM

The following recipient(s) could not be reached:

John Doe (Jdoe@problemdomain.com) <mailto:Jdoe@problemdomain.com)> on 4/14/2004 10:02 AM
Could not deliver the message in the time limit specified. Please retry or contact your administrator.
<4729.vespa61domain.local #4.4.7>


Any further suggestion would greatly be appreciated,
RmL

&quot;Adhere to your own act, and congratulate yourself if you have done something strange and extravagant, and broken the monotony of a decorous age.&quot; - Ralph Waldo Emerson

 

[GlenJohnson]

One thing Vespa61 and I discovered is the problem e-mail can't get pinged either. Not a bad nic, maybe corrupt tcp/ip stack. (Kinda have my doubts about the last, but doing a bit of grasping.) To early to tell, we just discovered it this morning.

Glen A. Johnson
If you're from Northern Illinois/Southern Wisconsin check out Tek-Tips in Chicago, Illinois Forum.

TTinChicago

http://www.johnsoncomputers.us

 

[xmsre]

Ah. This reminds me of the issue where a domain has two MX records, and the server the lowest cost MX record is pointing to is down. The problem is that I don't recall what the resolution was, I'll have to look through my notes. Anyone else remember?

 

[xmsre]

Firewall configuration. Here's a thread for the issue and solution using symantec's solution:

http://www.tek-tips.com/viewthread.cfm?SQID=745512&SPID=858&newpid=858&page=1