Using older versions of Outlook for Mac for personal email and calendar
Hello IT-guy-2020,
Greetings! Thanks for posting in Microsoft Community.
As per your description, l understand how frustrating it must be to experience Office 365 sign in issue. l would like to resolve this situation for you immediately. However, before moving forward, we need collect a little more information to better narrow down the issue for further assist.
Can you please tell me:
- What kind of Microsoft 365 subscription you are using now?
- What the version of Outlook do you have? See What version of Outlook do I have? - Microsoft Support.
Given that situation, we need do further troubleshooting in the meantime.
- Please confirm if you are able to login from the web following this link https://outlook.office.com
- Please share a full screenshot of the error message
- Please confirm if you are able to login to other office applications.
For security reason, we need collect above requested information via private message.
To view it, select your profile and click on view private messages as shown in below screenshot:
We look forward to your response. Thanks for your time and cooperation.
Sincerely,
Tammy | Microsoft Community Moderator.