I think the issue seems to be the mechanism between Dovecot and AD, so basically PAM.....
I adapted my pam.d file to this: # auth auth sufficient pam_krb5.so no_warn try_first_pass debug #auth sufficient pam_ssh.so no_warn try_first_pass auth required pam_unix.so no_warn try_first_pass # account #account required pam_nologin.so #account required pam_unix.so account required pam_krb5.so in the hope that this config would work: userdb { driver = static args = uid=501 gid=501 home=/mail/%u driver = static # args = uid=500 gid=500 home=/ZPOOL_1/%u # allow_all_users=yes } passdb { driver = pam } However I am still having issues :-( Regards, Kaya