Outlook 2016 doesn't accept password or app password

Just remove the account from Nine Folders and add it back in again after patching the app.

(Sorry for the delay in responding. I've been out all day and funnily enough my Microsoft email isn't updating right now!) :-D

Nine have released a 'fixed' version that seems to resolve the problem of Microsoft no longer accepting Base64 encoded text. Seems to work. I have asked Nine Support whether that means data is now sent as clear / plain text and to confirm that username/password are NOT sent as plain text. Awaiting their response.

I've also asked them to confirm I don't need to do anything in respect of my previous paid-for registration since I had to uninstall and reinstall and got the two week trial message when I did so.

I agree with about 80% of that . :D As an IT Pro from enterprise environments I've become accustomed to the feature rich full version of Microsoft Office standalone suite so I may be partial to that but I understand and agree with many of the reasons for using alternatives. I've got Thunderbird configured as a backup on the PC, and on Android I like Fair Email. I might check out 9folders since it has been mentioned numerous times here but straying on topic, a recap...

There is a server side issue with Outlook Email for many people, which is experienced differently by different people using different email clients and or different settings, and which in a very few cases can be worked around with specifica settings, and which Microsoft minimally acknowledges here: https://support.microsoft.com/en-us/office/outlook-and-other-apps-are-unable-to-connect-to-outlook-com-f4202ebf-89c6-4a8a-bec3-3d60cf7deaef

I encourage people experiencing this to click on "Outlook" at Office 365 at Down Detector: https://downdetector.com/status/microsoft-365/

Good catch on these open issues. Really appreciate you thinking about them. Would truly appreciate an update if and when you get an answer.

Thanks. Toss up between waiting and doing all the setup tasks with a new account on Nine. Having this information helps. Thanks again.