Exchange 2010 users getting long delays with outlook

[HMCTech]

Recently with no changes whatsoever Outlook has started to be very unreliable with constant "retreiving information" notifications and hanging. clicking on folders under inbox can take anything from instant to 30 seconds.

 

Doing performance troubleshooting tests on both the CAS and mailbox servers produce a few warnings which may or may not be a fault

 

The top 6 users account for 100% of the MAPI CPU usage on the server.

A potential issue with the RPC activity for some MAPI operations was identified.

 

Not certain what either means and not been able to find any specifics so far. any possible ideas on what causes this to start to happen?

[sukh]

Single server with all roles?

 

Top 6 users? How were these identified? Exmon?

 

Anything in the app logs?

 

Could be these users have a pluggin in OLK? Mobile Devies?

[HMCTech]

We have two boxes one os the mailbox store the other is the CAS, Hub.

 

I went through the Tool Box Performance troubleshooter and that was the only warning it came back with using diferent time lengths.

 

It started happening when term ended, within the first few days of the holidays when only ahandful were in. No one can install plugin for Outlook and we have had mobile devices connected for over four years now and nothing is prompting in the logs or event viewer that a device is causing an issue.

[sukh]

Still an issue?

[HMCTech]

Our SonicWall had a firmware update which decided to hammer our domain controller with so many requests that it was running at 100% all of the time. Changed that and Outlook hasn't been an issue since!