The Connection To The Microsoft Exchange Server Is Unavailable Outlook 2003 Calendar - Exchange 2010

We are migrating from Exchange 2003 to Exchange 2010. On the back-end we have first updated the server and are migrating mailboxes across from old to new.

Few problems but the main one is some users reporting that they get the error "the connection to the microsoft exchange server is unavailable".

I did some googling for this and found out that it could be an encryption setting so I turned this on, I think it was on the client. That did not help.

In the end I found this doc:

http://support.microsoft.com/kb/2299468

Basically, the problem is that opening multiple calendars in Outlook uses a large number of connections between the client and the Exchange server. You can raise this by changing a setting on the Exchange Management Console, you are basically changing the default connection throttling policy.

Alternatively, you can just get users onto the new client (2007 or above) as soon as possible. That's what we did.

Ironically, this only arises because in the old days people liked to have multiple calendars open to see when everyone was free. But since Exchange 2007, you can now see this when making an appointment and there is no need to use Outlook like this anymore. Maybe that's why the default connection limit is so low, to encourage users to use the new features.