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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.

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This can occur if the user has a lot of notifications or alters that they have not dismissed (snoozed instead) as each one can create a connection to the Exchange Server.

Is it every user that has this many connections, or just a few? If its just a few you might want to take a look at their work habits, are the constantly snoozing reminders etc?

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Pretty much every user has the problem. But it can't be that. I know everyone isn't snoozing 20 messages, but Outlook 2007 seems to create up to 30-40 connections when it connects to Exchange 2003, for most people. – user38654 Mar 25 '10 at 8:36

We have seen the behaviour you describe when the client has the TDSS malware installed. Lovely stuff, that malware.

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We had this problem with one of our remote sites during a period of poor connectivity. At times we were seeing 30% packet loss, and the dropping connections was enough to cause outlook to lose its connection (leaving it in a state of limbo) and create a new one, until the limit was reached.

How reliable are the mobile connections they are using?

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We're all in a fairly small office, the cell phones are on wireless (obviously) while the laptops are both on cable and wireless, and we have fairly good wireless coverage. – user38654 Mar 25 '10 at 8:37

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