imap-authenticator-alist

imap-authenticator-alist is a variable defined in `imap.el'.
Its value is

((gssapi imap-gssapi-auth-p imap-gssapi-auth)
 (kerberos4 imap-kerberos4-auth-p imap-kerberos4-auth)
 (sasl imap-sasl-auth-p imap-sasl-auth)
 (cram-md5 imap-cram-md5-p imap-cram-md5-auth)
 (login imap-login-p imap-login-auth)
 (anonymous imap-anonymous-p imap-anonymous-auth)
 (digest-md5 imap-digest-md5-p imap-digest-md5-auth))

Documentation:
Definition of authenticators.

(NAME CHECK AUTHENTICATE)

NAME names the authenticator. CHECK is a function returning non-nil if
the server support the authenticator and AUTHENTICATE is a function
for doing the actual authentication.