You may have noticed you’re no longer getting delivery or read receipts. this feature has been discontinued from Microsoft:

Delivery reports in Microsoft 365 and Office 365 allowed users and administrators to discover and view delivery information about mail messages. Delivery reports for users have been discontinued and there is currently no direct replacement. Delivery reports for administrators have been replaced by the Message Trace feature.

For more information, see these topics:

• Trace an email message

• Message Trace in Security & Compliance Center

• Message trace in the modern Exchange admin center

• Run a message trace and view the results in the Exchange admin center