Radu Hociung wrote:
I propose an alternative method, the "forwardmaster" method.
"Automatical per-user forwarder white lists", good idea.
IMHO better than trusted-forwarder.org or op=trusted.
Minor nits: If a forwarder publishes a sender policy it
doesn't guarantee that it actually checks SPF. For Meng's
op=trusted idea I've added some overhead for forwarders
who are also MSAs (RfC 2476), but probably you don't need
any of these ideas for your concept.
What you probably need need is to identify forwarders by
their HELO and IP against SPF or CSV or a "forwardmaster"
list of hardwired IPs (worst case).
Bye, Frank