Any to way to ensure valid domain in from address in outbound/outgoing mails?

Hello,

does anybody know how to limit the FROM (or REPLY-TO) address of outgoing e-Mails (mails to other than the protected domain) to be limited to the protected domains in MTA mode?

I have just verified that when I am sending from an internal host I can actually send with a from address containing any FROM address. Is it only me who considers this a problem?

Thank you and best regards,

    Jörg