On Mon, Nov 08, 2010 at 03:39:02PM -0500, Wietse Venema wrote: > > The right solution to this problem is a packet routing solution, > > not an SMTP message routing solution. > > Like setting the default route to the "right" gateway. That would > be robust only if those gateways perform network address translation, > otherwise who knows what path the return packets will take.
NAT at each outgoing gateway can ensure that the return packets come back to the right place. Or one can rely on the dead link disappearing from BGP routing tables (if the source address is "portable" and one's routers peer with the various ISPs that provide the various links). -- Viktor.