roaming user

Hi,

I have installed on 2 linux (debian and mandrake) Qmail + vpopmail + 
Courier-Imap ....  based on this very well done document :  
http://sylvestre.ledru.info/howto/howto_qmail_vpopmail.php

I have a big problem.
The roaming user is not working. When I want to send an email, it 
answer that I'm not authorized to send mail through that smtp server. 
As if tcpserver isn't wrapping the POP3 and IMAP connections to 
authentificate connections and add them to the tcp.smtp.cdb
What is strange is that if I stop the qmail service and I restart it, 
it works but only for the people which are connecting to the server 
just at this time.

The guy who made this howto tutorial can't help with my problem, it's 
too strange for him.
Then I'm asking you some help, please.

Arnaud