Hi, about 3 weeks ago I had to defrag the priv.edb on exchange server 5.5. Everything worked fine. We have remote users that access their mail using POP3 and leave a copy on the server so they can access using OWA. Even after the defrag there was no problem.
Some of the remote users were using the IP address of the server instead of the name. We changed the incoming and outgoing servers to the mail server name instead of the IP address (mail.company.com)
Now the messages are being downloaded again. My first thought was that the defrag re-numbered the message IDs on the server an that was causing the problem. However, it wasn't until the mail server name on the client changed that the messages started to download again.
I don't think by changing the mail server on the client would cause this.