Exchange connection issues

A third party application had strange issues with a new Exchange 2013 server.

Environment: Super Office 6.1, Exchange 2013, Terminal Server, Server 2003

Symtoms:

The Infobridge Synchronizer agent had issues connecting to the exchangeserver för certain users. Only strange thing we discovered was that the users that didn’t work came in the same order as the Infobridge database had structured the users. Like the first 34 worked and the the remaining 7 had ID like 34,35,36… in the dbo.

Solution:

Many conversations with Super Office, infobridge yet another consultant and the developmentdepartment,  it finally clicked

1. On the ExchangeServer add or change the following value
2. \\HKEY_LocalMachine\System\CurrentControlSet\Services\MSExchangeIS\ParametersSystem\
3. Create Dword(32) value named: Maximum Allowed Sessions Per User = 250
4. Restart Server or Information Store.

Now it’s important to note that the Exchangeserver had proper throttlingpolicies configured and didn’t alert to any events that indicated session issues.

I had similar issue when a procurve switch between an Exchange 2003 server and an office was being bonkers. That time it had to with the switch cutting of the sessions, forcing the client to initate new sessions without closing the old ones. But I really thought 2013 would be a leap forward in this sort of situation.

Why are these the default limitation on a Serversystem that should be able to support tens of thousands of users? And the do this sort of error on only 50….

References:

http://elderec.org/2011/07/exchange-2010-mapiexceptionsessionlimit-unable-to-open-message-store-2/