Quoting Richard Earnshaw <rearnsha@arm.com>:

> This is all quite disastrous on low-memory machines, I now need sendmail
> running on my machine just to be able to redirect local root mail to 
> myself (the main mail servers send root mail to the sysadmins), and that
> daemon is wasting nearly a Meg of RAM and a process slot (according to 
> 'top').  Postfix isn't any better in this regard.  It has something like
> three daemons running in the basic dumb-client configuration.

you can set the MTAHost to your hub, add the low-memory machine's FQDN to 
the hub's local-host-names (class w) and use a virtusertable to redirect 
the mail:
  root@low-mem.host address@to.redirect.to
and possibly also:
  @low-mem.host catchall@to.redirect.to
or:
  @low-mem.host %1@to.redirect.to

-- 
Christian Limpach <chris@pin.lu>