We are in process over moving our exchange 2003 infrastructure to a virtual ( hyper v) exchange 2010 infrastructure. it is a very simple move. we are going from simple exchange 2003 server ( all on one physical server) to simple virtual exchange 2010 server ( 1 cas/hub server and 1 mbx server)
we have got it working and i am in the process or slowly moving mailboxs from 2003 and 2010. what i have found is there is a delay from a user sending an e mail who is on 2010 to user on 2003 (up to 5 minutes). both the exchange 2003 and 2010 are in the same data centre so there is no distance involved. it is a simple 1 forest domain.
this only happens when sending from 2010 to a 2003 user. if a 2003 user sends to a 2010 user then it is instant as is 2010 to 2010
is this a known problem? are there any tips on troubleshooting this?