Using classic Outlook for Windows in business environments
Dear, Geraldine O'Malley Tyler Griffiths
Thank you for posting in the Microsoft Community.
I understand that you received an automated message regarding an issue with persistent error code 505 and apologize for the inconvenience.
Just to clarify with you first, if you received an email from the Microsoft Accounts team and the email address domain is @accountprotection.microsoft.com, you can trust the email and open it.
Regarding your feedback, you can check the validity of the email by checking the following area: Can I trust email from the Microsoft account team? - Microsoft Support
If you are still unable to confirm whether the email is official or not by following the steps above, we recommend that you delete the email as a precautionary measure to protect your privacy and security.
I hope the above information is helpful. We look forward to hearing from you.
May you be well
Ava.W-MSFT | Microsoft Community Support Specialist