[Mailman-Users] Problems with others domain-users

[Daniel José Miguel Rodrigues]

Hi
Sorry for my humble english but i need your help

I have a problem to send emails to others domain-users.
I can send emails to these users when i do not use mailman but when i use 
mailman the /var/log/maillog log this error message:

Recipient address rejected: Relay access denied; from 
test-admin at my-mailman.host to daniel.rodrigues at yahoo.com.br  

I use mailman 2.0.13-3 and postfix 1.1.11-5 in linux redhat 8.0
Docs an urls are welcome

Thanks