[Web-cyradm] cyrus or postfix problem

[Liviu Dragomir]

I'm using the entire engine postfix + cyrus + sasl + mysql + amavis +
clamav + web_cyradm etc etc 
and i want to use email adresses for usernames 
i mean if i have the email address example at domain.com i wat to use the
same for username 

i resolved that in cyradmin and cyrus 
i can login with user example at domain.com and everithyng is ok 
but i have problems with postfix 
when i receive an email for the example mailbox i receive the error
"mailbox not found" 
when postfix is receiving an email for example at domain.com is sending to
cyrus for user "example" 

what can i do ?