I have a barracuda server that receives mails, filter them and forward to a linux system running postfix.
Both machine have a public IP (static). The linux system is configured to be used as SMTP for sasl authenticated users as well, besides to be used as SMTP for the people on $mynetworks (permit_mynetworks in the smtpd_recipient_restrictions). Unfortunatley, some spammers, have found it and use to spam local recipients using the linux machine, avoiding so to be filtered through the barracuda system. I'm wondering if there is a way to allow OLNY local users or users belonging to the domains hosted by the linux server to use SMTP. Thanks MG
