Problem with smtp via postfix

I’ve installed virtualmin with script, install.sh, all is working fine, i can receive email, but if i try to send email, here there is the error.
I try to use smtp at mail.mydomain.com.
i’ve unchecked authentication and i get this error in thunderbird:
The mail server responded: 5.1.1. Receipent address rejected: User unknown in virutal alias table…

in /var/log/mail.log
NOQUEUE: reject: RCPT from host254-246-static.12-87-b.business.telecomitalia.it[87.12.246.254]: 550 5.1.1 <info@domain.it>: Recipient address rejected: User unknown in virtual alias table; from=<info@from.com> to=<info@domain.it> proto=ESMTP helo=<[192.168.0.100]>

Thanks for help…

neorf

i've unchecked authentication and i get this error in thunderbird:

This is exactly what is supposed to happen. You must authenticate.

Or are you saying you unchecked authentication because it didn’t work? If so, we need to know that error (and I’ll also ask if you’re using @ in your usernames). This error is everything working as intended, and there is nothing to fix.

Solved with this:

chmod 755 /var/spool/postfix/var/run/saslauthd

Full post @: http://www.virtualmin.com/forums/help-home-for-newbies/re:unable-to-send-mail-with-postfix-use-mail-clien.html