This is a colon-delimited list of authentication methods mutt may attempt to use to log in to an IMAP server, in the order mutt should try them. Authentication methods are either 'login' or the right side of an IMAP 'AUTH=xxx' capability string, eg 'digest-md5', 'gssapi' or 'cram-md5'. This parameter is case-insensitive. If this parameter is unset (the default) mutt will try all available methods, in order from most-secure to least-secure.
Example: set imap_authenticators="gssapi:cram-md5:login"
Note: Mutt will only fall back to other authentication methods if the previous methods are unavailable. If a method is available but authentication fails, mutt will not connect to the IMAP server.