I need input on how the new transparent SMTP proxy works for larger sites.
So - let say
1-20 domains
2-three mx records to public IPs
3-Three internal mail servers on private IPs mapped to public vis SNAT (must send on IP the MX is on)
4-Backup MX records point to other mail servers at site - SO domain 1 mx10=server1, mx20=server2
So How to configure smtp proxy so primary and backup mx records work to the correct servers. Especially since many sending mail server don't just user lowest mx they send to mail server that responds first. Thus, even if mx10 server is online some mail always gets to mx20.
What about loops if you set to follow mx won't proxy be sending to iteself ?
Help!