So actually SA does a pretty good job going down all received headers representing internal mail transfers inside an ISP given only the ISP's domain. So if you can get it to "trust" a user specified domain the user would only have to specify the ISP's domain and not any internal email hosts for it to work. I prefer it to be limited only to specified email address since the forwarding works is that a user specifies a particular email address to the forwarder to forward to, so there is no reason to "trust" the forwarder except for the specific email address email is forwarded to.
|