Users with mailboxes that have met the quota for their mailbox where they will get a warning are receiving the warning every 15 during the time window when the mailbox database is scheduled for online maintenance. I can't find anything in the event logs to indicate why this is happening. Shouldn't it just be sending 1 message instead of a message every 15 minutes?

There is a Warning Message Interval parameter that can be adjusted at the mailbox database level. Open the Exchange Management Console (EMC), select the properties of the mailbox database, choose the Limits tab.

Thanks!Someone please wack me over the head with the Captain Obvious stick.