smtp forwarding

[Philip Reynolds]

Eitarou Kamo <e-kamo at trio.plala.or.jp> 38 lines of wisdom included:
> Now then, I'm also using ipfw2. I would like to forward the smtp packet
> to the
> current(alive) mail server with priority. I mean that I'd like to
> forward the smtp
> packet to the secondary server when the primary server is down or panic.
> Is it possible? I'm wondering if ipfw can know the status of the mail
> server
> (dead or alive) in advance. And if possible, I expect the solution of
> the ipfw rules.
> 
> Assumption:
> mail domain is "@hoge.com(global)"
> primary mail server address is "192.168.100.4 (private)"
> secondary mail address is "192.168.100.5(private)"
> ipfw interface is "fxp0"

This can only be done properly at the application layer.

IIRC, Postfix can do something similar, with fallback_relay,
although I haven't looked into Postfix and load balancing since
early 1.x snapshots.

I'm not sure how qmail has developed on this front.

Regards,
-- 
Philip Reynolds                      | RFC Networks Ltd.
philip.reynolds at rfc-networks.ie      | +353 (0)1 8832063
http://people.rfc-networks.ie/~phil  | www.rfc-networks.ie