Office 365 Email Delivery has failed to these recipients or groups

popeel

This started from yesterday 13/07/2023. Nothing changes from OSTicket and the OAuth2 – Microsoft working fine and not expired.
Is this something from Microsoft Office 365 ? Perhaps Transport rule or any system changes?

We have not change any Transport rules for last month.

Delivery has failed to these recipients or groups:
xx My Name xxxx (xxxxxx@xxxxx.xxxx.xx)
The email system had a problem processing this message. It won't try to deliver this message again.

Diagnostic information for administrators:
Generating server: LO4P123MB6643.GBRP123.PROD.OUTLOOK.COM
xxxxxx@xxxxxxxx.xxx.xx

Remote server returned '554 5.6.0 Corrupt message content; STOREDRV.Deliver.Exception:ConversionFailedException; Failed to process message due to a permanent exception with message [BeginDiagnosticData]Content conversion: Corrupt summary TNEF content. ConversionFailedException: Content conversion: Corrupt summary TNEF content.[EndDiagnosticData] [Stage: PromoteCreateReplay]'

assassinlynx

I had this issue with my helpdesk instance. I ended up upgrading from 1.17 to 1.17.4 and that has fixed it. It may be worth attempting to upgrade your version to see if that fixes it for you.