I've my postfix mail server that work properly, but there is a problem with access and relay email from external clients to my internal domains.
I'll explain:

If from a external client (or from a telnet session) I connect to my postfix server, I can send email to all my internal domains without any type of authentication and control.
If from an external client (or from a telnet session) I woul like to send email to any external email address (so to an external domain) postfix require me to autenthicate (I suppose that this is the right configuration and my mail server isn't an open ralay).

I would like to set postfix to require authentication also for relaying mail to my internal domains.
Is that a correct configuration? And How can I do that?

This is my main.cf configuration file:
#smtpd_sender_restrictions = hash:/etc/postfix/access, reject_unknown_sender_domain
smtpd_sender_restrictions = hash:/etc/postfix/access
smtpd_client_restrictions =
smtpd_helo_required = no
smtpd_helo_restrictions =
strict_rfc821_envelopes = no

smtpd_recipient_restrictions = permit_mynetworks,reject_unauth_destination