Split from this thread.
@Saviniencyrano: Have you received any of these messages since then?
@Ankita Vaidya MSFT: Thank you for the support, I will answer your questions:
A screenshot of the email from Outlook (web):
A message trace does not show these messages, I selected my mailbox as the recipient and the last 24 hours as the period. About 90 messages should appear here. However, only regular messages are displayed.
Content-Type: multipart/mixed; --XXXXboundary text Content-Type: text/plain
Lorem. this is the body text
--XXXXboundary text Content-Type: text/plain; Content-Disposition: attachment; filename="test.txt"
this is the attachment text
--XXXXboundary text-- |