CAS Event Logs Application\MSExchange ActiveSync (1024) returned warning value Time: 8/30/2011 4:47:37 PM. Event description: User "Domain\"username"" cannot access their mailbox on Mailbox server "mailboxServer.hhmi.org" because access is denied.. I tried to disable/enable activesycn access, but that didn't clear error.

Hi cuttabutta, What is the version of your Exchange Server? For Exchange Server 2007, I have seen the similar issue, it was caused by Exchange 2007 server account is disabled for the mailbox server in AD. It can be resolved by the following steps: <1>Since Exchange 2007 mailbox server is disabled in “Exchange Domain Servers” group, you can enable it by this way: ADUC->Users->Exchange Domain Servers->right click on the disabled account and enabled it back. <2>Restart the Microsoft Exchange Topology Discovery Service on the affected mailbox Server. If this not fit for you, I suggest you use Exchange Best practices Analyzer to collect more information. Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com

ex2010

nothing is disabled. I will run exchange best practice analyzer

Hi cuttabutta, How about the issue? Did you get any related information after you run Exbpa? Thanks, Evan Liu TechNet Subscriber Support in forum If you have any feedback on our support, please contact tngfb@microsoft.com

I'm still seeing this, every once in a while a see a new user with this error, but they are able to access their mailbox. No one is complaining about mailbox access, i'm just curious whats causing it. I guess this can be closed. thanks for help.