Users in Office 365 need to be granted send rights in order to relay. When ESS sends an email it can be sent as anyone in the organization. The problem is most companies don�t want to do blanket permissions and allow end users send rights in Office 365. Not only is that time consuming, it is a security risk.
ADMIN RESPONSE
Sep 21, 2023
Thank you for your submission. This was�implemented in the Q1 2019 product update.
