In my Exchange 2003 in SMTP protocol and SMTP virtual Server, Properties-Messages there is a option to redirect messages with email address not resolved to a other host. Where I can find this option in Exchange 2010.

Here is the answer. http://blogs.technet.com/b/exchange/archive/2010/01/28/3409250.aspx Cheers, Gulab | MCTS-MCITP Messaging: 2010 | MCTS-MCITP Messaging: 2007 | MCC 2011 | Skype: Gulab.Mallah

So you could do it with transport rules. Condition: sent to users that are inside or outside the organization or partners Actions: redirect the message to address Exceptions: null Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.