Outlook 2016 doesn't accept password or app password

@Robdstef,

If you have M365 Personal the best experience would be to use the M365 Outlook that is part of your subscription. It connects with modern auth and is not affected by this recent issue. If you prefer Thunderbird, it would be best to follow the guidance of Thunderbird to use OAuth as noted in this article, Microsoft OAuth Authentication and Thunderbird in 2024 | Thunderbird Help (mozilla.org). I will keep sharing feedback to the service team to work on addressing the issues with basic auth, but you could skip all that with the other two options you have. Modern auth is also a more secure connection method so worth the effort to switch if you can.

It is very relevant because Microsoft themselves, as I referenced, are the ones suggesting the use of "New Outlook" as a way of avoiding this authentication issue, but there are several of us here going back to page 13 with privacy and security concerns (notably with regards to non-MS e-mail accounts) in regards to how "New Outlook" works (very differently as a proxy) from traditional e-mail clients as per its terms and conditions such that it is not a viable option for us. Hope you understand. Cheers.

I left a comment yesterday because I was having problem connecting a new employee mailbox (Outlook 2016 desktop to 365 hosted mailbox). I did everything possible (reg hack) even when it does not apply to Outlook 2016 but still couldn't get the new mailbox added into Outlook 2016. The error says something like "we can't add the account right now..." (not the exact words).

This morning I continued to troubleshoot the problem but didn't succeed so I gave up, again.

About an hour later, the user sent me an email. She said she was able to use Outlook 2016 to access her mailbox. That tells me the problem is on the back end. I did nothing on the PC to get Outlook 2016 to connect. It didn't connect earlier and suddenly it connects successfully. Whatever it is you guys are doing is the source of the problem.

Glad to see this topic back on trend. In late January, MS obviously implemented programatic changes. Since this is such a widespread issue, that MS seems incapable of solving, why not roll back to when this problem didn't exist, and then slowly implement changes, pausing to see if the problem reoccurs?. Then they'll know the culprit. Did this back when I was in charge of the IT department at my company. Maybe a lot bigger than we know, but a solution exists. MS needs to assure all possibilities are on the table.

Yup, same problem here.

My company offers a CRM to its users, a lot of people can't connect their personal Outlook.com accounts any more because of this issue.

We're patiently waiting for Microsoft to fix this, but they don't seem to be willing to do much.