Is it possible to setup my centos 6.5 so all outgoing port 25 is run through a proxy. I have incoming smtp/port 25 coming to my mail server through HAproxy but i would like the outgoing to do the same so the receiving mail server sees the connection coming from my load balancer IP. i have been searching the net for last hour but can't find any examples or setups.

1 Answer 1


While it might be possible, make sure your mail server identifies itself using the name assigned to your haproxy server.

By design SMTP is resilient to network and server failures. I can't see a good use case for putting an email server behind haproxy. It might make sense to put and IMAP or POP server behind haproxy.

If you have a single email server, then you can do what you wish much simpler with iptables rules. If you have multiple email servers, each should have a unique IP address. These addresses should have DNS entries that pass rDNS for the domain name they identify themselves as. The mail servers can (usually) use a domain name different from that of the host they run on.

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