Eudora…

Pull down "Tools," pick "Options."

Fill in the fields in the "Getting Started" page; they'll migrate to the other pages, where they can be modified as required.
Don't forget that the "Login name" contains "@mycrib.com"!
Check the "Allow authentication" box if it's required by either your ISP or your domain host.

The "Incoming" page is where you select POP3 or IMAP, and other convenience options.

Authentication isn't always implemented correctly, but the "Sending Mail" page is where it's configured.
If it doesn't seem to work, try turning it off...