How to bypass O365 hardening for Teams invitation forwards

Created by Yves Lacombe, Modified on Tue, 22 Dec 2020 at 10:19 AM by Yves Lacombe

Issue: you've implemented O365 hardening as per this article here and teams invitations sent by your users are being blocked by the hardening (you're getting an "Invalid IP Address" NDR)

Solution:  You need to add an exception to the rule that basically bypasses the hardening if a meetingmessage header element is present in the message.

See example below: