Exchange 2010 - calendar changes delay sending notifications

Exchange 2010 - single server, SP2.

Some users are sometimes having issues changing or declining meeting requests - most often when the affected user is *not* the organizer.

On Tuesday, User1 scheduled a meeting for Friday and invited User2.
User2 accepted on Tuesday.

On Friday, before the meeting time, User2 proposed a new time, then declined.  (I witnessed User2 do this - so I know for a fact he did it when he said he did).

User1 did not get the change and cancel emails until 2 hours later (well after the meeting, and some confusion).

Message tracking shows the emails to User1 only at the 2-hours-late time.  Nothing was sent when I saw User2 propose the new time and then cancel.

This is one example, but not the only condition.  I have not been able to replicate it on demand.
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Can you reproduce this issue frequently?  Do you have cached exchange mode running on the client mail applications?  (assuming Microsoft outlook).
snowdog_2112Author Commented:
I cannot reproduce the issue on demand - it seems to be "random", not every meeting, not every change/decline.

The affected users would be running the default autodiscover settings:
cached mode: yes
connection: https
[  ] On fast networks, connect with HTTP, then TCP
[X] On slow networks, ...
Authentication: basic
If there's a fast link between the clients and the exchange server, try disabling cached exchange mode temporarily to see if the problem still exists.
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snowdog_2112Author Commented:
I'll try this with a test client - the user most frequently experiencing this connects via several devices on several networks each day, bouncing from meeting to meeting at different locations, and using laptop, desktop, ipad, and iphone (sometimes all at once).
snowdog_2112Author Commented:
No issues since installing Exchange 2010 SP3 UR2.

Will post back if we see it occur again.  For the moment, it appears the Service Pack/UR may have resolved the issue.

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snowdog_2112Author Commented:
no issues reported since updating to Exchange 2010 SP3 UR2

Thanks for the input!
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