[imp] How to force plain authentication ?

[Olivier Le Lain]

Hello,

I can't succeed in loging on to my new Imap server with imp.
It's a cyrus one with allows gssapi (kerberos) PLAIN and LOGIN 
authentication.
If I remove gssapi from sasl_mech_list: in /etc/imapd.conf , everything 
works fine (imp users  can connect).
But if I set it back, imp login fails and imp/test.php gives me indeed :

/
     * Trying protocol imap/notls, Port 143:

           ERROR - The server returned the following error message:

           Kerberos error: No credentials cache found (try running 
kinit) for
           localhost.localdomain/

It looks like imp doesn't try to switch back to plain or login 
authentication.

This is also the behaviour of cyradm. It refuses to login me if I don't 
have a valid kerberos ticket by default, but  I can force LOGIN. See :

/cyradm -u olivier imapserver
cyradm: cannot authenticate to server with  as olivier/

/cyradm -auth  LOGIN -u olivier imapserver/
/IMAP Password: /

Is there a way to do the same with Imp, ie force the "-auth LOGIN" 
equivalent somewhere in the conf ?

Thank you.