cannot add account in outlook in office365

[frankie225]

I want to add an account in outlook 365.

However, an error message was prompted saying that my security certificate was expired.

What should I do?

[#2]

@frankie225 

I would suggest that you try to use the tool here in setting up your account:

https://support.office.com/en-us/article/About-the-Microsoft-Support-and-Recovery-Assistant-e90bb691...

Might be helpful if you take a screenshot of the error message and post it here. Another thing is if your email address domain is used as a website as well, verify if the certificate of the website is still valid.

[#3]

@RaizelX

In addition to what was suggested above, also try and disable any firewall/antivirus on your network. Then check the behavior  

[#4]

@RaizelX 

A long time ago my Microsoft Account was a Google email address: xx@gmail.com . Then I created xx@outlook.com account with the previous address as backup. I recently removed Gmail address as secondary. However now Outlook Microsoft 365, when I added xx@gmail.com as Gmail account, adding xx@outlook.com does nothing - no error - it seems outlook account is still recognized as gmail one through my old PST files stored in the disk. Windows 10 Outlook have no such problem- Gmail and Outlook accounts are separate.

What shall I do get Outlook.com account in Outlook Microsoft 365?