Another day… another seemingly random problem with Exchange 2007.
In case you didn’t see my post yesterday, I am currently migrating a client from Exchange 2003 to Exchange to 2007.
The install went ok, and last night I moved all users mailboxes across to the new server.
Happy that everything had gone to plan I visited the client expecting no problems to have be reported.
However, no user had received any mail in outlook since the previous day, including e-mails sent internally, but they were all receiving their emails on thier BlackBerry handsets (which were all setup on BIS to get mail from OWA).
I logged onto the exchange 2007 box, expecting to see that some of the exchange service were not started, but they were all on and working.
I sent a message to myself from one users Outlook, and it arrived in my own (external) mail account fine.
I sent one back…. it never arrived…
Then i noticed that her Outlook was displaying a message in the bottom right hand corner stating that it was connected, but that it had last updated at 9am, but it was now actually 9:40am.
I logged into Outlook web access as an affected user, and low and behold my reply mail was sitting there, just not appearing in her outlook.
So outlook was connected, but not updating. The mail was actually getting in and out fine, just not into Outlook.
It ws then I noticed a heap of “sync errors” in outlook. Reading the message, it indicated that I had too many emails open, and an error code that when googled pulled up a single result.
That single result did however lead me to another article that helped me solve the problem.
The problem was that all users were in cached mode…. each open folder, additional mailbox, calendar reminder etc constitutes a “session” between Outlook 2007 and Exchange 2007.
In thier wisdom, Microsoft have hard coded a very small number of permitted simultaneous sessions, so as to try and stop the Exchange server becoming overloaded…
You can of course override this setting, but adding some items to the registry… which I did and it solved the problem immediately.
The Microsoft article I followed is here: http://support.microsoft.com/kb/830836