libmail-srs-perl - 0.31-6 main

The Sender Rewriting Scheme preserves .forward functionality in an
SPF-compliant world.
.
SPF requires the SMTP client IP to match the envelope sender
(return-path). When a message is forwarded through an intermediate
server, that intermediate server may need to rewrite the return-path
to remain SPF compliant. If the message bounces, that intermediate
server needs to validate the bounce and forward the bounce to the
original sender.