Hi,
We recently installed Exchange 2010 (1 CA/HT server, 2 Mailbox servers), and currently have a co-existence with our existing Exchange 2003 server. At this time, only a very small percentage of user mailboxes (<1%) have been moved to the 2010 server, as we are still testing to ensure proper operation. What we are noticing is that the users who have mailboxes on the 2010 server are getting a substantial delay upon receiving mail, anywhere from 1 to 20 minutes, seeming independent of message size or source (internal or external).
Based on what I can tell from the message tracking information, the message gets delivered to the 2003 server first, and then is routed to the 2010 server, which is where the hangup is. What I am unsure of is, (1) why is the message not delivered directly to the 2010 server and (2) why is there such a delay in this routing?
Messages being sent "from" the 2010 users appear to route just fine, and show up instantly in the mailboxes of the 2003 users. SMTP send connectors have been set up on the 2010 server seem to working correctly.
Also, when checking the queues on the 2003 Exchange server, the default Routing Group Connector between the 2003 and 2010 servers has a constantly fluctuating high number of messages in it, with a size ranging anywhere from 5,000 KB to 4,000,000 KB. Given the small number of mailboxes we currently have residing on the 2010 server, I'm sure this isn't standard mail traffic. Could this be caused by Public Folder replication process of some kind? Could it be the reason behind the latency in mail delivery for the 2010 users?
Thanks