Postfix delivery problem

Hi,

I've got a problem with postfix.
I created a virtual domain and an account using Jamm.
my domain : domain
my account : user

When I try to send a mail to that user, (sendmail user@domain) postfix drop the
mail saying that user "user" can't be found on domain "domain". It means that
postfix search for a user "user" instead of searching "user@domain" as the
account name is "user@domain" and not "user" (using a webmail, I've to use
"user@domain" as login, "user" doesn't work).

I think I made a mistake in my configuration but I don't see what...
If someone can help...

PS: sorry for my english :)


-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now. 
http://productguide.itmanagersjournal.com/