Sometimes Exchange Online sends messages in TNEF. Most often it happens if sending tenant expects that the message supposed to be handled by another Exchange, so it is true for internal messages sent by a tenant to self.

TNEF (Transport Neutral Encapsulation Format) is a proprietary email format, so those messages are ignored by Xink ReRouter by default.

Xink TNEF message handler unpacks such messages before passing them on. After unpacking the message is converted into regular MIME format, then it passes regular signature injection mechanisms and goes back to Office 365 in MIME format. 


In most cases this conversion doesn't change anything from end user point of view and considered safe. But Exchange online administrators should be aware of conversion and understand what happens in background.


Please remember that ReRouting settings are cached by email processing farm, in might take some time for the changes to take effect.

PS: If you are using Android Smart Phone you still need to use the Marker {EMAILSIGNATURE}

Add/Replace signature without marker 

http://support.xink.io/support/solutions/articles/1000247340-how-to-configure-rerouting-using-the-web-console-office-365-#marker