-o smtp_bind_address6=1:2:3:4:5:6:7:8

-o smtp_bind_address6=1:2:3:4:5:6:7:8

rotate1  unix -       -       n       -       -       smtp
          -o syslog_name=postfix-rotate1
          -o smtp_helo_name=domainone.com.br
          -o smtp_bind_address=173.111.111.1

rotate2  unix -       -       n       -       -       smtp
          -o syslog_name=postfix-rotate2
          -o smtp_helo_name=domaintwo.com.br
          -o smtp_bind_address=173.111.111.2

user = postfix
password = mypassword
dbname = postfixdb
hosts = localhost
query = SELECT transport FROM transport_random WHERE domain = '%d' AND status='1' ORDER BY RAND() LIMIT 1

Column "transport" = rotate1, rotate2, rotate3, rotate4 (etc)
Column "domain" = sender domains (replaced by %d)
Column "status" = boolean (0 or 1) if is enabled the transport.

transport = rotate1 | domain = mydomain.com
transport = rotate2 | domain = mydomain.com
transport = rotate3 | domain = mydomain.com

inet_interfaces = 66.66.66.67, localhost