Why are Return-Path headers added by SRS differ? For example:
In case of multiple forwarders, the first forwarder sets SRS0 marker. The SRS0 marker tells other forwarders that SRS has already happened. The second forwarder changes SRS0 to SRS1, slaps on the first forwarder's domain, and leaves everything else untouched. Subsequent forwarders just change the domain at the end.