Outgoing Mail to Some Destinations Stuck in Queue

Thoughts;

Destinations could be Blacklisting your IP. Check one of the many blacklist checkers on the www and also check to see if you have an open relay going.

Is open relay on the RELAY RESTRICTIONS of the ACCESS tab of SMTP properties?

http://support.microsoft.com/kb/895853

This is a great article on mail issues - check about half way down for instructions on testing for open relay.

I believe what michael is stating - could be true.
Check on site: http://www.spamhaus.org/pbl/index.lasso
Also, please check if your Exchange server has a PTR record registered on your ISP box.

Have you tried to send an email using telnet to one/some of these domains?

I didn't try telnet.  I'm not sure how to do that since I would be telnetting to a server I'm not sure of the name and I have no control over.

One thing I did find out:

Our network has 2 gateways to 2 different service providers, ServiceA and ServiceB.

ServiceA is a provider we've had for awhile; ServiceB is new.

When I change the gateway on the mail server to the firewall connected to ServiceB, I have the problem on a few destinations described in this posting.

When I change the gateway on the mail server back to the firewall connected to ServiceA, the problem goes away.

But that is not a fix.  I'm dropping SerivceA soon, so I've got to get this working on ServiceB.

Right now I have a single message to a single destination hung up in the queue.  I'll try telnetting.

I wonder if this could be a DNS problem.  The DNS server on our network uses root hints.  Should I switch that to a forwarder?

Does this new service provider of yours hold your new MX record along with PTR record for your domain ?? Please get this part of the picture clear.

No.  Our PTR records and MX record are registered separately, at register.com.

And our incoming mail is routed first to appriver.com, which does our spam blocking.  I only tell appriver the ip address on our firewall that corresponds to our mail server.  But that's for incoming only, of course.

Outgoing, we dump straight out to the internet (though outgoing mail is not a process I full understand).

"No.  Our PTR records and MX record are registered separately, at register.com."

So is this information same with both Service Providor.

"Outgoing, we dump straight out to the internet (though outgoing mail is not a process I full understand)"

Which is your Smart Host server ?? on SMTP Connector.

in Exchange System Manager
Administrative Groups
Servers
<server name>
Protocols
SMTP
Default SMTP Virtual Server
Properties
Delivery tab
Advanced
Smart Host

This value is blank.  There is no Smart Host.

Are you using DNS at the same location to send emails OR you are having a SMTP Connector created to send emails ???

Sorry for my absence.  I got pulled away on something else.  Now I'm back on this.

To answer your most recent question, Exchange Geek, I have an SMTP protocol which I assume is the same as an SMPT connector in the Exchange Systems Manager.  Other than that, I don't think I understand your question.

The exchange server NIC card has a DNS setting which is the single DNS server on the in-house domain and that has a bunch of forwarders for handling outside DNS.

Is that what you mean?

This is getting worse.  More and more emails are building up in my outgoing queues.  More remote sites are appearing to never accept our emails.  I can clear it by switching the mail server gateway to an alternate service provider.  But that's a temporary solution.  We lose that provider soon.

This would get worst buddy, if you allow us to troubleshoot the issue better - having such an absence would delay and break the rhythm to troubleshoot this issue.

SMTP Connectors: http://technet.microsoft.com/en-us/library/aa996625(EXCHG.65).aspx
SMTP VS: support.microsoft.com/kb/303734

So, we would like to know how are these emails going outside. Using DNS / SMTP Virtual Server / SMTP Connector ??

I have an exchange server (2003) and an SMTP protocol under that server and under that an SMTP virtual server.  DNS is handled on my domain controller using DNS forwarders.

I don't see any mention of a "connector".