IPV6 Guide for sending email from specified IP?

==== Required information ====
- iRedMail version: 0.9.2
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Ngnix
- Linux/BSD distribution name and version: Ubuntu 14.04 LTS
- Related log if you're reporting an issue: N/A
====

http://www.iredmail.org/docs/send.out.e … esses.html - How do specify a IPV6 and IPV4 for outgoing mail?

Thanks