451 4.4.0 Primary Target IP address responded 421 4.2.1 unable to connect.

Hello Experts:

I am running Exchange 2007:  I have a problem with sending email to a customer with the messages getting stuck in the que:  The error message says: 451 4.4.0 Primary Target IP address responded 421 4.2.1 unable to connect.   Attempted failover to alternate host, but that did not suceed.  Either there are no aternate hosts or delivery failed to the all alternate host.

Does this message indicate a problem on my end or the customer's end?  All other mail from my mail server is going out and in with no other problems.

Thanks for the help.

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That usually indicates a problem with the remote end. 4.x.x errors are usually temporary errors.

huntersp3Author Commented:
Hello Sembee:

I called our customer and he says he has been getting emails from other people.  Any other ideas would be welcomed.  I ran the mail flow Trouble shooter and I get the problem of Domain onealsteel.com is remote domain to which commserver1 is possibly having trouble routing messages through a smpt connector.  Another problem is The pointer record localhost does not match any FQDN of the SMTP instances on server commserver1. This may cause routing problems when remote servers have a filter to map an IP address to a server name.

I have checked the dns settings and see the a record for the commserver1 and its associated pointer--I am puzzled.  Any ideas is appreciated.
huntersp3Author Commented:
Also another issue surface in the troubleshooter was Port 25 did not repond on server mail.onealsteel.com.  Unless the SMTP port has not been changed on server mail.onealsteel.com mail flow problems will occur.
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If I had a $1 for everytime I heard that it wasn't a problem because they are getting email from other people, when in fact it was a problem at their end, I would be very rich, sat on a beach with a very fit blonde.

What your customer didn't tell you is that they are a message labs customer.

Although if message labs see that configuration they will get told off, as they haven't their own server in the MX records, which you shouldn't do.

One of the message labs towers in the tests I did was not responding correctly, so it would appear to be a problem with the remote end.

Your server has done an MX record lookup, and because the record it is using has a server on the end that is giving out temporary errors, it doesn't go looking for another server.

Try flushing your DNS cache and see what happens then.
Otherwise your customer needs to get on the phone to Message Labs and see if the servers they have in the MX records for their domain are still valid.


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huntersp3Author Commented:
Thank you, Sembee...you are the best.  I wished I had half of your knowledge!  I will keep pressing them.
I am having the same problem with multiple domains. How can I tell if they are a message labs customer?
trg-sysadminInfrastructure ManagerCommented:
I just wanted to add to this post that our we added our server container in AD to our McAfee EPO and the policy for preventing mass mailing worm blocked port 25.  We added the exception and all is well again.  

So, check to make sure antivirus or firewall is not blocking port 25.
*sends one fit blonde to Sembee*
Sembee = Awsome
hey guys sorry to bust in on the thread like this but i have a similar problemstuck queue. im fresh out of thoughts. trying to do a migration from sbs2003 to sbs 2011. the mail is stuck in the queue and it wont go out. i flushed dns, ran bpa on both but cant seem to get it working. any thoughts?
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