Exch 2010 - Internal Delivery Problem to Distribution Groups

Exchange 2010 server -- single domain, single site -- is not able to deliver messages to certain Distribution Groups from local users.

The Queue Viewer shows about 100 messages stuck. The entries of some columns are:

1. Next Hope Domain: Mailbox Store 2 > "cn=MyDomain,cn=routing groups,cn=MyDomain,cn=administrative groups,cn=foxy,cn=microsoft exchange,cn=services,cn=configuration,dc=MyDomain,dc=com"
2. Delivery Type: SmtpRelayToTiRg
3. Status: Retry
6. Last Error: 451 4.4.0 Primary target IP address responded with: ""421 4.2.1 Unable to connect"" Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts."

By the way, this server -- not managed by us -- has two NICs with this kind of IP settings:
   IPv4 Address. . . . . . . . . . . :
   Subnet Mask . . . . . . . . . . . :
   Default Gateway . . . . . . . . . :

   IPv4 Address. . . . . . . . . . . :
   Subnet Mask . . . . . . . . . . . :
   Default Gateway . . . . . . . . . :

How do I go about troubleshooting this? BTW, is there any way to change the Queue Viewer so I can see Recipients rather than Senders?

Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

You should be having option to add remove columns like sender, size, etc. from View menu. Also, please provide your environment details.
AkulshAuthor Commented:

Column options don't have 'To Address", only "From Address".

About enviroment:
- Exch 2010 on Win 2008
- Was in coexistance with Exch 2003 till recently
- Since Next Hop Domain entry seemed to point to routing group on Exch 2003, I asked the people to bring back that server. Now messages have been 'transferred to that server" according to Message Tracking, but still not being delivered.
(What else you would like to know?)

Now my question: What is so unique about Distribution Group delivery on Exch 2010 since other recipients are getting their email?
AkulshAuthor Commented:
After old Exch 2003 was brought up, I moved Recipient Update Service, both instances, to the Exch 2010. Also I removed the routing group connectors by cmdlet:
Get-RoutingGroupConnector | Remove-RoutingGroupConnector

So now those messages are under Unreachable Domain. This shows that they were trying to go thru the Exch 2003. But why? And why only for Distribution Groups? How can I route them locally?
AkulshAuthor Commented:
Further UPDATE:

I found the culprit!
The Expansion Server for certain distribution groups was set to be the old Exchange 2003 server. Now I have specified the Exchange 2010 as Expansion server. So new email to these DGs is now flowing. However old messages which are in the queue do not want ot rethink about expansion server and still want to go to old no-good server.

Is there anyway these messages in the queue can be sent to the newly specified correct expansion server -- the local server? Thanks.


Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
AkulshAuthor Commented:
No one else was able to help, but I still want this solution available in KB since it might help other having DG delivery issues.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.