I really got a big problem. I have been running two windows 2000 servers as domain controllers PDC, BDC for a longer time. Alongside an exchange 2003 was running on the basis of a windows 2000 server. Now we decided it was time to upgrade the server landscape.
We installed two core domain controllers based on windows 2008 R2 server and a server running Exchange 2007.
We then intended to move the mailboxes and public folders from exchange 2003 to exchange 2007. The move of a mailbox was smooth. When we tried to send email from user with his mailbox on ex2003 to the moved user on ex2007 it was successful. But answering this email back to the user on ex2003 did not work.
Next was to try a telnet session on port 25 from ex2003 to ex2007 and vice versa. This worked well. Each user could see the email in his mailbox.
Now what I assume is that exchange 2007 tries to authenticate at the ex2003 with a ticket that was issued from the windows 2008 R2 domain controller with a higher encryption level.
My admin tells me that we simply need to move the mailboxes and export the public folder and reimport them afterwards.
But I wonder if there is a way to bring Exchange 2007 to send mail to exchange 2003?
I appreciate any help!