Zimbra Outgoing SMTP IP per Domain

1. Add the following line in “/opt/zimbra/postfix/conf/main.cf”

sender_dependent_default_transport_maps = regexp:/opt/zimbra/postfix/conf/sdd_transport_maps.regexp

2. Create the file “/opt/zimbra/postfix/conf/sdd_transport_maps.regexp” and add the domains as below

/@example\.com$/           example_com:

3. Once done edit “/opt/zimbra/postfix/conf/master.cf.in” and add the below code

example_com unix -       -       n       -       -       smtp

-o smtp_bind_address=<dedicated IP>

-o smtp_helo_name=mail.example.com

-o syslog_name=postfix-example

4. Restart postfix.