As SPF is implemented, MTAs that check SPF must account for any forwarders. One way to handle forwarding is to have the forwarding MTA rewrite envfrom to a domain they are authorized to use.

The package also include a package for sign and verify sender addresses with message ID (SES). There is also a base class for sendmail socket server (SocketMap) available.

See http://www.openspf.org/SRS for details.

These are the binaries of the module.