It is my understanding that the sender email address for the Purchase Orders must be a MediusFlow email address for users on domains for which DMARC validation has been activated: The mail servers of users (Company A) will tell receiving mail servers to drop emails claiming to come from Company A while in fact being sent from the Sendgrid domain (email service partner used by MediusFlow).

This means that suppliers cannot 'reply' on emails generated by MediusFlow without manually inserting a reply address.

Better support for DMARC email verification would be helpful.