We've had a problem at work where users sometimes randomly can't connect to exchange. I've found out that it's because they reached the limit of 32 concurrent logons. I increased the maximum allowed connections by adding the key "Maximum Allowed Sessions Per User" in HKLM\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem.
But I'm not sure if this is a real good fix. Looking at the logons some users has as many as 15 logons with the exact same logon time. I know for sure that Outlook 2007 does this, as I was watching them while a user connected with Outlook after a restart on the Exchange service. Every user also has an iPhone connected to exchange, I don't know if these cause the same thing.
Is this normal? Could there be a bug in the software? (The Outlook 2007 has nothing configured, except added the user, pure vanilla installs). The users are mobile, and when Outlook generates up to 15 connection every time it connects, and I've read (no sources, sorry) that Outlook doesn't time out connections before 2 hours. I might have to set this number real high to prevent it from being a problem.