Andrew Johnson wrote:
> 2 other alternatives :-
>
> Hardware loadbalancer (such as Alteon or F5)
>
> Linux as a loadbalancer - there are various iptables options that can be
> used to loadbalance connections, though I'm not sure how well these work if
> one of your email servers goes down.
>
> At least with the Alteon load balancers, they can do helath checks and look
> for smtp banners to decide if the server is available.
>
Another free and secure alternative:
OpenBSD's hoststated as a loadbalancer.
hoststated is a host status daemon for server load-balancing. It moni-
tors groups of hosts for availability, which is determined by checking
for a specific service common to a host group. When availability is con-
firmed, Layer 3 and/or Layer 7 load-balancing services are set up by
hoststated.
