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 - - n - - smtp -o smtp_bind_address=1.1.1.3 -o smtp_helo_name=customer3-dom.tld -o syslog_name=postfix-customer3 ..... next .....
In main.cf add sender_dependent_default_transport_maps line:
sender_dependent_default_transport_maps = regexp:/etc/postfix/sdd_transport_maps.regexp
Don’t forget to create ip aliasing for each ip address in smtp_bind_address
reload/ restart postfix
# service postfix restart
to set for server-wide for all clients
You want smtp_bind_address=66.66.66.67 and inet_interfaces=all
or inet_interfaces=eth(whatever) that 66.66.66.67 is on.
and RESTART postfix