Create file called sdd_transport_maps.regexp: /@customer1-dom\.tld$/ customer1: /@customer2-dom\.tld$/ customer2: /@customer3-dom\.tld$/ customer3: ..... next ..... In master.cf create special transport called customer1, customer2, customer3….and so on customer1 unix - - n - - smtp -o smtp_bind_address=1.1.1.1 -o smtp_helo_name=customer1-dom.tld -o syslog_name=postfix-customer1 customer2 unix - - n - - smtp -o smtp_bind_address=1.1.1.2 -o smtp_helo_name=customer2-dom.tld -o syslog_name=postfix-customer2 customer3 unix - […]