Maildir or mailbox

dear milist 
i have install qmail with cekpasswd , i use script like this:
#!/bin/sh
env - PATH=/var/qmail/bin:/usr/local/bin
tcpserver -v -R 0 pop3 /var/qmail/bin/qmail-popup mydomain
/bin/checkpassword  /var/qmail/bin/qmail-pop3d Mailbox 2>&1 |

/var/qmail/bin/splogger pop3d &

and running , try to telnet localhost 110 , user xx , pass xx and  
get
error
-ERR this user has no $HOME/Maildir
Connection closed by foreign host.
tcpserver: end 892 status 256
tcpserver: status: 0/40
i want use Mailbox because old use Mailbox ,
and one againt how to convert Mailbox to Maildir
thank's