Minor Exchange 2007 / Outlook 2010 fail. User was reporting that after setting an Out-of-Office rule people were not receiving the message. This applied to internal and external senders. Ran down the usual troubleshooting steps- reset Outlook 2010 client rules, reset users Outlook 2010 profile, move user to another Exchange DB, etc. Nothing solved the issue. I finally started digging a bit deeper and discovered the Exchange RulesQuota which limits the total size of enabled rules associated with a mailbox to 64KB by default in Exchange 2007. Running a Get-InboxRule -Mailbox $username and discovering that this user already had ~140 rules and finding that each rule takes up about .6KB, bingo- we have a problem.

After a quick Set-Mailbox -identity $user -RulesQuota 128KB and user testing, problem solved.

Where’s the fail here? Exchange, Outlook, and Outlook Web Access all failed to alert the user that the rule was not taking effect. Guessing by the estimated size of his rules (~84KB) I can only imagine that he had several that were not working.