But now that I had this working connection in TenFourBird, I looked at the settings it had auto-configured for the account to work, and copied those to Mail. However, I didn't like TenFourBird's visual layout so much. So I got TenFourBird which is apparently much nicer in terms of setting things up: All it wants is my e-mail address and password, and it sorts the rest of things out automatically. No matter how I tried to follow instructions I found online, I couldn't get Mail to work properly with the server configuration: Incoming or outgoing server was always offline when I tried to send something, even if it was online briefly before that. This gave me a code that works as a password when logging in from the mail application. Set up two-factor authentication for the outlook account (a massive pain, their website is the opposite of user friendly and they make you go to and fro)
I just set up Outlook with two-factor authentication which allowed it to briefly get online in Mail but christ that Outlook it's like using a Windows computer: Now they randomly spam the address with verification requests no matter what I do, and when I go to the webmail settings via my main computer, they dare to constantly spam me with "tell us what you think about us" pop-ups. Protonmail (free) doesn't seem to support anything else but webmail, so that doesn't serve my purpose.
I'll check out TenFourBird, but I'll still have to understand the setup jargon somehow.
Then back to the same issues I had before, which is that one or the other server is spontaneously offline and I have no idea of what else to do about the settings It's not like I understand what any of the settings mean anyway, all I'm doing is blindly trying to repeat what I see in online guides, and I still never know if it's right because of course software this old doesn't look like the things in the guides. I managed to briefly get the Outlook one to work, so it downloaded one e-mail from inbox and I managed to send one.