Using Classic Outlook on Windows for personal email, calendar, and contact management
Hi Pinkfelix12
May I know which mail client users using to send email Request a Read Receipt, is it Outlook Web App or Outlook desktop client?
If they have any antivirus software installed, please temporally disable it.
Do they have any antivirus add-in such as McAfee/Kaspersky add-in enabled?
If users are using Outlook desktop client. To exclude issues caused by Outlook add-ins you may try using Outlook in safe mode to check this issue.
To start Outlook in safe mode.
- Choose Start > Run.
- Type Outlook /safe, and choose OK.
You may also ask users to send email Request a Read Receipt using Outlook Web App to see whether the problem still occurs.
Moreover, as an Office 365 admin you can run the message trace to determine whether any forwarding rule is triggered causing this issue.
Note: Please do not call phone number above that is a known Tech Support SCAM phone number. We have spam reported and deleted that post.
Best regards,
Shyamal