In my Exchange 2010 lab, I came across a handful of messages in the submission queue. All of them were for accepted and declined meeting invites and nothing else and all of them for journaling only. Here is the error that was in the queue viewer:
Last Error: 400 4.4.7 The server responded with: 550 5.6.0 M2MCVT.StorageError; storage error in content conversion. The failure was replaced by a retry response because the message was marked for retry if rejected.
As this is a lab, I used the following script to easily remove them from the queue, here is the script:
Get-Message -Server EX2010A -Filter {FromAddress -eq "<>" -and Status -eq 'Retry'} | Remove-MessageWhat this does is go and look at my Exchange Server EX2010A and with a filter go and remove anything from <> that is in a retry status.
After the above was run, Exchange was happy again. I recently updated to RU31 and I’m guessing it can be a bug in this rollup or something went wrong but after several reboots this issue has not cropped up again.
Hope it helps.