On 15/04/2023 13:53, Jeremy Harris via Exim-users wrote:
>
> Exim does talk the inbound-proxy protocol tha HAProxy apparently uses (or can use):
> https://exim.org/exim-html-current/doc/html/spec_html/ch-proxies.html#SECTproxyInbound
Thinking further, this (HAProxy with Proxy-protocol as a frontend for an MTA,
with the HAProxy routing based on SNI) has additional complications. Because
the ESMTP connection has to (for port 25) negotiate TLS using STARTTLS, you're
asking that HAProxy run that part of the ESMTP protocol, so that it can see the
SNI. It'd have to replay that ESMTP startup down the connection to the backend,
as far as the TLS Client Hello - or be a full ESMTP endpoint. I don't know if
it's that clever.
--
Cheers,
Jeremy
