Share distribution groups between two separate Exchange Organizations--Exhchange 2003

I have two servers running Exchange 2003 in separate exchange organizations and separate AD forests.

Currently we have Server A forwarding any unresolved mail to Server B.  This is working as a "shared namespace" scenario.  Mail flow is working.

Our migration plan calls for us moving the Mailbox from Server A to Server B, then deleting the mailbox from Server A.  We then planned on creating a contact on Server A for the deleted mailbox.

My question is....I want to migrate users from Server A to Server B.  How can I maintain user's distribution group membership so that their new mailbox on Server B receives email when mail is sent to a Server A distribution list?

Example, UserA now exists on Server B as a mailbox enabled user.  User A's contact now is a member of a distribution group on Server A named "Office Supplies"  

I try to send an email to the distribtuion group on Server A and get the following error:
   A configuration error in the e-mail system caused the message to bounce between two servers or to be forwarded between two recipients.  Contact your administrator.

Any thoughts?
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.

Vishal BreedProgram ManagerCommented:
That's correct!! This is by design and you cannot change it. You need to change the way of working.

UserA which was moved on ServerB, is part of DL on ServerA.
Hence when u send email from ServerB,
- DL of ServerA expands on ServerA (check DL properties - you cannot change it)
- email is received by ServerB
- ServerB finds, original sender of ServerB is sending email from ServerA.

This is a known problem in shared hosting scenario!! If possible, try seperating UserA from DL of ServerA. In other words, do not include user's from exchange organization A in DL of exchange organization B in case of shared hosting.

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
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.