My SMTP server is being abused because external adresses can send emails to adresses like email@example.com, firstname.lastname@example.org etc...
I would like to restrict the usage of those adresses only by internal users ( could be from network ) that have the same domain name like email@example.com.
With these restriction external user like firstname.lastname@example.org couldn't send emails to email@example.com but firstname.lastname@example.org could. And email@example.com could send an email to firstname.lastname@example.org.
I hope that it is clear enough... I realy don't know how to implement that in Postfix.