authentication, outgoing, IMAP

Hi all,

I have this in ".wl" (and no authentication setting in ".folders"):

  (setq elmo-imap4-default-stream-type 'ssl)
  (setq elmo-imap4-default-authenticate-type 'clear)

When I change the first to

  (setq elmo-imap4-default-authenticate-type 'login)

It says authentication failed when I try to fetch mail.

So: is this a problem? This question-answer on stack exchange:
https://stackoverflow.com/questions/24950225/emacs-wanderlust-imap-password-authentication
seems to suggest the password is safe, but the WL manual says it is
sent "in raw format" if the setting is "clear".

Anything else I can try? I'd like to know a bit more before I try to
talk to the service provider people.

/Tomas