Thank you. The version I find on Google Play seems to be from 2016, which, in itself, doesn't have to matter. I have other apps of that age.
As Outlook.com / Outlook on the web (or whatever they call it this week) uses OAuth2 for its 2FA (on my job, anyway), support for which was only recently added to the "canonical" K-9, I might, however, run into the same authentication issues as Airmail presented me with (though, hopefully, handling it nicer than just terminating with no clue, as Airmail currently does).
K-9 "proper" seems to lack all support for composing rich text. I am having a look at FairEmail at the moment. Its Wizard failed to set up my Outlook account, complaining something about the admin maybe disabling SMTP or something, which didn't seem accurate, so I'll have another look at it tomorrow or so.
In K-9 and k-@ I had to generate a password to authenticate them. My email is from yahoo. It only worked to generate a password when I disabled my wifi and used the 5G directly from astro ( I used the brave browser ). I followed the instructions below:
Sign in to your Yahoo Account Security page.
Click Generate app password or Generate and manage app passwords.
Enter your app's name in the text field.
Click Generate password.
Follow the next instructions ( below the app password ).
Click Done.
When using my wifi the password the password was not generated .See error below:
( Yahoo Generate App Password -> Sorry, this feature is not available right now!).
It only worked when using directly 5G from astro as I said.
k-@ for me is the best email app.
Please take a look at the attachment