Sending, receiving, and organizing email in Outlook.com
Thank you for getting back. I will suggest some fixes. Please do them step by step.
Try switching the Email to Plain Text instead of HTML as a troubleshooting step to verify.
The setting is below:
- Open The Gear icon > Settings.
- Go to Mail > Compose and Reply.
- Change the message format to Plain text.
Also, if it does not solve the problem, The back end team can remove your account from the blacklist.
In Outlook on the web, go to the Help tab > Help, type your search terms, then click the Yes button for 'Still need help' at the bottom.
I hope this information helps. If you have any more questions, don't hesitate to reach out.
Otherwise, if your problem is resolved, please take a moment to rate the answer. Wishing you good luck!