#5.1.1 SMTP; 550 Address unknown> #SMTP#


I am in the middle onf an Exchange 2003 to 2007 upgrade and have moved the Services like SMTP, OWA etc to the new server.

I have moved a couple of mailboxes accross and now when emails are sent to those email addresses with mailboxes on the new server the sender gets a undeliverable messsage:

#5.1.1 SMTP; 550 Address unknown> #SMTP#

Those users on the old server can received mail?

Please can you help.


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.

James HIT DirectorCommented:
Can you try to have the user send without using the cached email address?
juleswaleAuthor Commented:
The Users can send out but not receive mail.
Sunil ChauhanLead AdministratorCommented:
hey have to placed a receive connector in 2k7 and a send connector in 2k3?
The Ultimate Tool Kit for Technolgy Solution Provi

Broken down into practical pointers and step-by-step instructions, the IT Service Excellence Tool Kit delivers expert advice for technology solution providers. Get your free copy for valuable how-to assets including sample agreements, checklists, flowcharts, and more!

juleswaleAuthor Commented:

I have just been told that all users cannot received Mail, and yes there is a routing connector between the two.
Sunil ChauhanLead AdministratorCommented:
can you double check if there is a receive connector on hub server
When you say there is a routing group connector, is this a two way connector? When I perform transitions from 2003 to 2007 or 2010 I always delete the automatically generated routing group connector and create my own,

New-RoutingGroupConnector -Name "Interop RGC" -SourceTransportServers "Hub2010.contoso.com" -TargetTransportServers "Bridgehead2003.contoso.com" -Cost 100 -Bidirectional $true

Open in new window

Taken from


Alternative you need to review the message tracking logs to see what's happening, Exchange 2003 sends and email to Exchange 2007 via the routing group connector just like if you send or receive mail externally, Failed mail can be diagnosed in the same way.
To send mail between Exchange 2003 and 2007 you do not need a send connector or a receive connector, all communications occur via the Routing Group Connector.

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.