VSTO Outlook addin MailItem.MessageClass property reset for sent email after it sync back from O365 account RRS feed

  • Question

  • We have an VSTO outlook addin which handle every sent email. After successful processing of email we set own MessageClass property value (replace IPM.Note with our own class). Using O365 account we found that after message synced back from server it will reset MessageClass value back to IPM.Note

    Is there any special reason for that ?

    When using Category , i.e. set a category after processing, it will not reset categories property value after message synced back from server.

    Wednesday, May 15, 2019 8:38 AM