They way I see it now in a one domain many user system there is typically one MTA and SA facility. Users and Administrators will train and tweak their SA configurations to fit what they need.

Now lets say you need to use zimbra to host/scan mail for 2 or 3 domains within your company. The needs and tweaks for each domain may counter the needs of others.

I know this is an exaggeration but lets say that 1 domain is a company reselling ****** and another domain is for cancer awareness. As you can see the whitelist/blacklist and Bayesian logic may conflict abit in this comglomeration if they both share the same MTA and SA facilities.

What I was thinking was creating multiple MTA servers/instances. Each one would serve an individual domain.

Has anyone tried this approach?

Does anyone have other approaches?