I’ve just spent a few days diagnosing a strange Exchange 2003 issue for a client.
The client had several users who were not able to connect their Outlook to Exchange, out of several hundred users, only a small percentage had this problem, they had nothing in common.
We saw various errors in the Exchange Server event log for a few days, then this one started to appear
Event Type: Error
Event Source: MSExchangeIS
Event Category: General
Event ID: 9646
Mapi session "<SNIP>" exceeded the maximum of 32 objects of type "session".
Which was the start of the break through. A few investigations led to a dead end, apart from one regarding TCP/IP off load engine. Its supposed to off line TCP/IP processing to seperate hardware on the network card, or something, it doesn’t really matter as it doesn’t really work!
In Service Pack 2 for Windows 2003 Microsoft rather silently released something called “Microsoft Scalable Networking” which is touted as a similar system. Unfortunatly again, it doesn’t really work, again.
There is a blog post on “You had me at EHLO“, the internal Exchange blog about this exact issue. Summarising the blog post, it says, if you have a brand-spanking-new server, install Windows 2003 SP2 and Exchange 2003, don’t expect it to work. The issues listed are endless, well almost.
If you can’t be bothered reading the spurl, this fixes it
Netsh int ip set chimney DISABLED
It’s something to do with the TCP Chimney stuff that the Scalable Networking installs, and that is as technical as I am going!
Hope it helps!