Aspose.Email version: 16.12.0.
Scenario: User creates message in Outlook; adds 25 PDFs and sends internal message.
Issue: Aspose.Email somehow changes message structure and Exchange cannot process message afterwards. User receives NDR.
NDR (message is attached):
#554-5.6.0 Corrupt message content 554 5.6.0 STOREDRV.Deliver.Exception:ConversionFailedException; Failed to process message due to a permanent exception with message Content conversion: Corrupt summary TNEF content. ConversionFailedException: Content conversion: Corrupt summary TNEF content. ##
There were no issue on Aspose.Email 6.6.0.0.
Unfortunately, you need lab with Exchange transport agent in order to replicate the issue. Though you may already have it after testing the following issue https://www.aspose.com/community/forums/thread/596250/ndr-from-exchange-server-with-content-conversion-error-for-message-with-outlook-item-from-drafts-fol.aspx
Also I found another issue that, I think, is a result of the same bug.
Scenario: I use EWSClient to send the same message, that resulted in an NDR in the environment with Exchange transport agent. This time NDR is not generated, but Exchange still considers TNEF part to be invalid, because Outlook shows "winmail.dat" attachment instead of a list of PDFs. If I use Aspose.Email 6.6.0.0 - no issue.
Attached sample project to demonstrate, that message comes with winmail.dat attachment.
Thanks,
Alex Shloma