SPF: SRSWhy SRS is neededRFC 1123 introduced two very convenient but easily abused features: relaying without regard to recipient (open relays) and forwarding without regard to sender. Both features have been abused to the point of unusability. Open relays have been suppressed via blacklisting. SPF stops forwarding without rewriting, but it does so on an opt-in basis. If you, as a recipient do not check S
