ISPman + CourierIMAP + maildrop + Postfix

I'm struggling with them: after some days of intense work (yes, I know this is Christmas time also here in Italy :O( )
I finally have it working with courier: I can succesfully login to ispman web interface, create a domain and add mail users to it.
Then if I telnet to port 110 and give the proper username and password of this new user I can succesfully login.
Nice! 
But now I'm facing this problem, I tried to solve it myself but without success, so I hope that someone will be so kind to help me:

If I try to send a mail (via telnet to port 25) to this new user things go wrong:

My Server Name: virgilio.draksoft.com
The domain just added: azienda3.it
The new user: [email protected]

Here is the contents of /var/log/maillog:

virgilio postfix/qmgr[6524]: 483C113B19: from=<[email protected]>, size=374, nrcpt=1 (queue active)
virgilio postfix/pipe[6530]: 483C113B19: to=<atestoni_azienda3_it-gH+WsCr1+wQDEN4ujrZYptvLeJWuRmrY@public.gmane.org>, orig=<[email protected]>, relay=maildrop, delay=16, status=bounced (user unknown. Command output: invalid user specified)

then postfix send a notify to the sender of user unknown

I am sure of my courier-imap configuration: not to sure of postifix and not sure at all of maildrop

Hope someone will help me

Thanks since now!




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