Just trying to understand a couple of things:
-Just to keep this simple -
a.) Have a gateway server = gt.MyDomain.com
--> Using webservices <---
b.) Have the "real " SM server = real.MyDomain.com
If the real Sm Server is down or unavailable.... how does the gt.MyDomain.com server "know" which email addresses are real, and which are not (since the "real" server is off-line). Does the gateway (gt.MyDomain.com) - keep a cached version of legit users??? How does it know??
Whitelist. Does the "gateway" server know anything about whitelist - or approved emails?
If so, and the "real" SM server is down, what does it do.