Salam, I added a new transport rule to forbid internal organization users to send to outside (internet addresses). I added the distribution list and its members, when I enabled it the users residing on Exchange 2010 could not send to users residing on Exchange 2003. My question is. What is the definition of inside/outside organization in Exchange 2010? If the term organization means "Exchange Organization" then how can I add the current users on 2003 to support my transport rule? Thank you, Kindest regards.Abdullah^2

Hi, I think it might be because exchange 2010 treats exchange 2003 as external org, try this : n the EMC, in the Mailbox section, under Properties, Mail Flow Settings, Message Delivery Restrictions, you can set the Accept or Reject to be "Only senders in the following lists." If you select everyone in the GAL, they'll be able to send internally. Do let us know if this doesn't help Ripu Daman Mina | MCSE 2003 & MCSA Messaging

Salam, Sadly this didn't help, well if that's the case I keep my transport rule disable till I move all Mailboxes as Exchange 2003 is still handling rejected requests using a customized connector. Anyway, thank you for the help.Abdullah^2