In the previous versions of Exchange Server we cannot play with the mailbox rules limit that is only 32kb (http://support.microsoft.com/kb/886616). Using Exchange Server 2010 we can do that through Exchange Management Shell. Let’s see how to do that..
The cmdlet utilized to set up the mailbox is called set-mailbox:
Let’s change the user Anne to 256KB limit using set-mailbox.
Set-Mailbox annec -RulesQuota:256KB