Unity messages are delayed for some users

[rala]

Installed Unity 3.1.4 with exchange 5.5 joined the existing exchange 5.5 site.

For some users the MWI is not coming on and messages are not getting delivered to them. When I look into the MTA of Unity exchange server these messages are in queue to the main exchange server. Any help.

[lindborg]

Unity hands all outside caller messages off to the MTA for delivery to the appropriate mailbox. check the event log for errors (RPC and RPC bind back errors are a dead give away for this type of problem, DNS issues are also common here). If there are RPC or DNS issues on the network messages can languish in the MTA queue on a box for hours or days before they're delivered to the home server.

Here's a good article talking about how to troubleshoot MTA issues in general:

http://support.microsoft.com/default.aspx?scid=kb;EN-US;q247133