The store driver failed to submit event ... mailbox ... error 1012

Ever get this message?
Want to know what mailbox it is?
In the Exchange Powershell:
Get-MailboxStatistics -Identity (all the numbers after 'mailbox')


If you run the cmdlet and get a blank space under StorageLimitStatus, this is 'by design', it seems to be a common error when you migrate the mailbox from 2010 to 2013. The current (12/14) work around is to move the mailbox to a new database.