Hi again! Thanks for the info. First, I doubt you are computer illiterate, you seem to know what you are doing, and there is always more to learn, even for the most experienced users. That said, I’m sure you have talents I can only dream of having!
Well, the first thing I would try, is to click on the top menu, Mail > Accounts, click on your mail account, then to the right, the far right tab, click on Server Settings.
If the username (Usually the email address) or password is blank, I’d enter it there.
Once done, you might see a “Save” option on the bottom right of that window, click that. (If no Save option, you can close that window.
Once done, on the top menu, click Mailbox > Take All Accounts Online (If its selectable), and year by sending an email.
If that doesn’t work:
To hopefully spare you some time, I’d likely bet on a keychain issue, so, since you know the password, (Make sure you also know the passwords to any other accounts that use that email if so, (Such as your Apple ID, etc.).
Quit the Mail app.
Open Finder > Applications > Utilities > Keychain Access, (You can also click the magnifying glass (Spotlight Search) and search for it).
In there, it usually defaults to “Login Keychain” and “All Items”, which is what we want.
On the top right of the window, you’ll see the search option.
In there, type in your email address, from the results below, you can delete any that say “Application Password” in one of the columns, or, as long as you know all your passwords just delete all.
(You can select the items, then select from the top menu, Edit > Delete).
Once done, I would restart the computer for good measure, then, instead of opening Mail, open System Preferences > Internet Accounts, and click on your email account.
If it asks for the password, you can enter it there, If not, you can open Mail, and once prompted, enter the password for the account.
