554 5.2.0 Error - AdditionalRenEntryIdsEx is too large and requires streaming

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We are using Exchange Online in a hybrid environment with Exchange 2016 (Version 15.1 ‎Build 2375.7)‎


We are experiencing a recurring 554 error with specific users. The error seems to occur only with reply emails that contain symbols in the subject. So, for example, if a user replies to a message and Outlook adds 'RE:', the error will occur. After removing the ':', the reply will go through with no problem. The error seems to come and go on its own, sometimes resolving itself before we can dig deeper. And, so far, it only happens with the same handful of users.


Remote Server returned '554 5.2.0 STOREDRV.Deliver.Exception:StoragePermanentException.PropertyTooBigException; Failed to process message due to a permanent exception with message [BeginDiagnosticData]Exception encountered initializing default folder. PropertyTooBigException:
The object data is corrupted. The value of property [0x36d90102] AdditionalRenEntryIdsEx is too large and requires streaming.[EndDiagnosticData] [Stage: OnPromotedEvent][Agent: Conversations Processing Agent]'


So far, we have tried the following fixes (some of these were done before we discovered it was an issue with symbols in the subject line)

  • Clear all rules from the mailbox
  • Remove any unneeded Office add-ins
  • Running the Disable-RemoteMailbox command, waiting for the mailbox to show up as soft-deleted, then running Enable-RemoteMailbox
  • Moving the mailbox to a different database using New-MoveRequest
  • Removing any attachments from the message
  • Formatting the message as plain text

Looking on the interwebs, I've not seen any other reports of this exact error—plenty of 554 5.2.0 errors but none with this same diag data.

Ideas or suggestions would be appreciated. 


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