Preserve the Correct Source IP When Forwarding Mailcow TCP Traffic

Thu, 07 May 2026 00:10:22 +0000

When Mailcow runs on a separate machine, forwarding its TCP traffic through HAProxy can leave the logs showing the forwarding layer instead of the connecting client. That defeats the point of checking the mail logs when the original source IP matters.

The service still receives traffic, so the forwarding path can look healthy at first. The problem becomes visible when investigating delivery, abuse, rate limits, or client behaviour and every connection appears to originate from the proxy instead of the real sender.

Haproxy - Tag - Dimas Maulana

Preserve the Correct Source IP When Forwarding Mailcow TCP Traffic