We have been experiencing nonstop Event ID 9646's on our Exchange server. They occur roughly once every 10 minutes or so, and there's no pattern to the users it occurs from that I can see. All of our desktops are on a VLAN; the Exchange server is on a separate VLAN. There's no firewall or anything between the desktops and Exchange.We are running Exchange Server 2003 SP2 with a mix of Outlook 2003 and 2007 clients, all on Win XP Pro SP2. The Exchange server is running Win 2k3 SP1.Any ideas on what could be causing this? Thanks!

Maybe this one will help. http://support.microsoft.com/kb/830836/en-us Why different VLAN's? Getting a lot of multcast traffic?

Can you copy and paste the full text of the message you are seeing? Just change your server name and anything that might identify your internal systems or real user's names.

Thanks for the replys guys.OK, this is the error we're seeing. This error occurs every 10 minutes or so, and it's for a different user each time. We have a few hundred users total, and all of them show up in this error at some point. So this isn't a case of any one user abusing their email privilages. =)Event Type: ErrorEvent Source: MSExchangeISEvent Category: General Event ID: 9646Date: 8/10/2007Time: 8:57:07 AMUser: N/AComputer: <ExchangeServer>Description:Mapi session "/O=SomeOU/OU=SomeOtherOU/cn=Recipients/cn=SomeUser" exceeded the maximum of 32 objects of type "session".For more information, click http://www.microsoft.com/contentredirect.asp.For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.I've read that people have seen this exact problem when clients are connecting to Exchange from a remote site through a Netscreen firewall, if that helps. However, we don't have a firewall between our Exchange server and the users, just a Cisco switch. Any other ideas? Thanks again!

Any other ideas guys? I would like to get this issue resolved if at all possible. Thanks for your help!

Hi Try applying the SP2 or increasing the Exchange deafult limits according to: http://support.microsoft.com/?kbid=830829 K