Gnus auth with username being prepended to domain

Question

I'm trying to solve the problem of Gnus asking you to type a username which it then prepends to the IMAP domain, i.e. preventing Gnus from making username typed at prompt [e-mail] into [e-mail]@mail.bar.com.

All the guides I've read online specify something like this for setting up login credentials:

Place a line like the following in ~/.authinfo

machine imap.gmail.com login [e-mail] password your-password port 993

Following that, I added a string that looks like this:

machine mail.foo.com login [e-mail] port 993

This gets me good behavior (prompt for password only), but still prepends the whole username to the machine address. Worse, when I try to change something and repeat the login, I get an error Wrong type argument: wholenump, nil.

My gnus.el file has the following for IMAP:

; IMAP
(setq gnus-select-method
      '(nnimap "mymail"
               (nnimap-address "mail.bar.com")
               (nnimap-server-port 993)
               (nnimap-stream ssl)))

Answer 1

The prompt is hard-coded in the source (nnimap.el):

(defun nnimap-credentials (address ports user)
  (let* ((auth-source-creation-prompts
          '((user  . "IMAP user at %h: ")
            (secret . "IMAP password for %u@%h: ")))
         (found (nth 0 (auth-source-search :max 1
                                           :host address
                                           :port ports
                                           :user user
                                           :require '(:user :secret)
                                           :create t))))
    (if found
        (list (plist-get found :user)
          (let ((secret (plist-get found :secret)))
        (if (functionp secret)
            (funcall secret)
          secret))
          (plist-get found :save-function))
      nil)))

So it seems like the only way to change this is to redefine the function and modify the prompt to be just "IMAP password for %u: ".