We recently had an issue on an Outlook 2010 client on Exchange 2010 , where when the user went to create an inbox rule they received the following alert.
“One or more rules could not be uploaded to Exchange server and have been deactivated. This could be because some of the parameters are not supported or there is insufficient space to store all your rules.”
Basically this is due to each mailbox by default having a rule limit size of 64KB.
We increased the rule size to 256kb for the user in question and then they were able to create additional rules.
Get-Mailbox username | Set-Mailbox -RulesQuota 256KB