We are utilizing a SonicWall Email Security 200 appliance which has been routing mail to our Exchange 2003 Server for the past several years. Several months back we installed a new Exchange 2007 Server and were running the 2007 and 2003 in a mixed environment with the SonicWall ES200 still routing the mail to the Exchange 2003 server. We have reached the point that we want to remove the 2003 server all together, so we transferred all mailboxes and information over the 2007 server. The last item on the list was to change the SonicWall ES200 to route the mail to the 2007 Server, we changed the IP address within the SonicWall and saved. After the change was made we were not receving any mail, all mail sent from the outside was getting bounced back to the sender saying the recipient could not be found. We created a new Receive Connector in Exchange 2007 allowing anonymous and full relay from the IP address of the SonicWall, but his had no effect we were still not getting mail.We changed the routing back to the Exchange 2003 server and it is currently working, but we need to get this issue resolved and take down the 2003 server. Any suggestions, we are fully stumped!Thank You!

First I would make sure smtp traffic is working on your Hub Transport Server. http://support.microsoft.com/default.aspx/kb/153119Then I would look at your receive connector rule, verify that it is allowing port 25 from the Sonic Wall IP. It could be an authentication issue from the Sonic to the Exchange Server. Is the Sonic trying to authenitcate using TLS or anything? You may need to check the box on your Receive Connector that it is Externally Secured.BP

Finally we figured this out. We forgot to remove all authentication options from the Receive Connector, once all the authentication menthods were removed (because the SonicWall doesn't support any authentication to connect to the SMTP server) mail started flowing. Thanks! --DUH--