Microsoft 365 admin center: Bring your own domain to use for Microsoft 365 product emails
Email notifications from products within Microsoft 365 are sent out to users in various ways. In many cases the emails are sent out from the user but there are system emails, like alerts, batched, or digest emails. These are sent from various product-specific no-reply email addresses, like no-reply@sharepointonline.com, no-reply@planner.com, no-reply@project.com.
Opting into this change means that administrators can select a verified domain to use for these emails. All products and features mentioned in the supported products link provided below can utilize this feature across Microsoft 365 and the support article will be updated as products onboard to utilize the setting. Emails will be routed to your Exchange Online instance within your tenant and the emails will then be sent out to your users from your tenant.