Hi,
I am looking at setting up a multiple postfix SMTP servers for a single domain. Below is my requirement, I would appreciate if someone out there could guide me to achieve this using postfix..

1. Want to setup 2 postfix SMTP Server with 1 POP3 Server.
2. Server1 will host POP3 & SMTP services for domain "metallica.one". (IP: 1.1.1.1, MX: mx1.metallica.one)
3. Server2 will host only SMTP services for domain "metallica.one"
(IP: 1.1.1.2, MX: mx2.metallica.one)
4. Server1 & Server2 will be used as load balancing for sending mails. (either manual settings in email client, or auto-loadbalancing is still preferred).
5. Mail received for domain metallica.one on Server2 should be pushed/forwarded/relayed to Server1 where POP3 services are running.
6. Outgoing mails for other domains from Server2 should be sent directly to the other-domain-recipients without relaying to Server1.

Thanks,
Satish

What's to explain? You already know about having multiple MX records although you don't load balance them other than setting equal MX priorities. As for the backup MX, there are many specific guides out there for this, e.g. http://www.howtoforge.com/postfix_backup_mx

This backup mx will work good for incoming mails (for domain metallica.one) when the mx1 goes down.

Can I use this backup mx2.metallica.one server for sending out mails for other domains? If yes, How do I configure user authentication (for SMTP)on mx2.metallica.one (Since all user accounts are created on mx1 server).