Apple mail: account name overwritten by "John Appleseed"

It's the pre-stuffed email address in Contacts, for as long as my memory goes back.

Why it's flipping is another matter, like the auto-suggestion of an email address I haven't used in a year, or the URL that I never ever typed being suggested in the browser.

I'm open to suggestions on how to get rid of such phantoms, without killing auto-fill suggestions entirely.