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> Hi,
>
> I have a question regarding Domain MX record and physical SMTP Loadbalancer.
>
> In my infrastructure we have several Postfix machines with local mailboxes.
> Each system sending messages to relay servers using internal relay domains
> with MX records. My team colleague told me that we will not use anymore
> local relay domains with MX records but Virtual host (with preconfigured
> relay systems behind) and F5 loadbalancer to transfer message from Postfix
> servers to the relay hosts.
>
> I would like to know Your opinion about it ? I know that MX record has been
> designed to avoid problems like E-mail loop etc.etc. Till now its working
> perfect for me.
>
> Does loadbalancer will not affect smtp communication ?
The load balancer MUST provide Postfix with the remote SMTP client
IP address. Postfix has support for doing that with:
- HAproxy protocol (uses the Postfix smtpd_upstream_proxy_protocol
and smtpd_upstream_proxy_timeout features).
- nginx (uses the XCLIENT protocol).
If your load balancer does not support one of the above protocols
then Postfix will not work properly, because all SMTP connections
will have the IP addres of the load balancer instead of the real
client.
To prevent mailer loops, configure:
/etc/postfix/main.cf:
proxy_interfaces = the loadbalancer external IP address(es)
With these things taken care of, load balancers should work.
Wietse
