Forwarding of calendar appointments from a DMARC projected domain fail when using Office 365
When receiving a calendar appointment from a DMARC protected domain (domain1) and forwarding this appointment to another domain through domain2 this results in an NDR.
550 5.7.23 The message was rejected because of Sender Policy Framework violation -> 550 5.7.1 rejected by DMARC policy for <domain>
The forwarding adds a Sender header so the message is send as <domain2> on behalf of <domain1>.
But uses the authentication (SPF+DKIM) of domain2 to send as domain1.
This violates the DMARC specification as the message now originates from domain2 but the From address (which is used by DMARC) is stil set on domain1.