[Dovecot] Dovecot config

[Dien Phan]

Hi,

I've installed dovecot 1.0.13 on FreeBSD 6.3 RELEASE and now trying to 
configure it. Below is my config file:

$ dovecot -n
# 1.0.13: /usr/local/etc/dovecot.conf
log_path: /var/log/dovecot.log
info_log_path: /var/log/dovecot-info.log
protocols: imap
ssl_disable: yes
disable_plaintext_auth: no
login_dir: /var/run/dovecot/login
login_executable: /usr/local/libexec/dovecot/imap-login
mail_location: maildir:~/Maildir
dotlock_use_excl: yes
maildir_copy_with_hardlinks: yes
mail_plugins: antispam
imap_client_workarounds: delay-newmail outlook-idle netscape-eoh 
tb-extra-mailbox-sep
auth default:
   verbose: yes
   passdb:
     driver: checkpassword
     args: /var/MailRoot/bin/dovecot_xmail
   userdb:
     driver: static
     args: uid=vxmail gid=vxmail home=/var/MailRoot/domains/%d/%n 
allow_all_users=yes
   socket:
     type: listen
     master:
       path: /var/run/dovecot/auth-master
       mode: 384
       user: vxmail
plugin:
   antispam_signature: X-DSPAM-Signature
   antispam_trash: Trash
   antispam_spam: SPAM
   antispam_dspam_binary: /usr/local/bin/dspam
   antispam_dspam_args: --user;%u

We are using a web mail software that allows users to login either as us 
'abc' or 'abc at domain'. The problem is: when a user logs in as 'abc' 
(without domain part) dovecots creates a directory 
/var/MailRoot/domains/abc and check mail there (as I understand because 
%d is blank).
My question is how to config dovecot so it automatically add default 
domain %d is blank.

Thank you for help.
Dien Phan