I've configured the krb_authentication plugin and it works great. I'm setting $_SERVER['REMOTE_USER'] and $_SERVER['KRB5CCNAME'] properly and I'm able to login to IMAP. However, I have a problem with sending emails via SMTP. When I authenticate using Kerberos, Roundcube doesn't know the user's password. Because of that, I cannot pass it on to SMTP, so I cannot use PLAIN login. It looks like there is not support for GSSAPI for SMTP.
Am I missing something or it hasn't been implemented yet?
Thanks