SPF is an addition to the Internet email infrastructure that sholud make it harder to send spam. libspf-alt is a C library that implements SPF. It includes a daemon, spfd, that can be used to add SPF support to Exim, my mail server of choice. This version of spfd is much smaller and faster than the Perl package. I wasted a bunch of time making a Debian package for it. To use SPF with Exim, install libspf-alt0 and libspf-alt0-bin, and then follow the directions included in /usr/share/doc/libspf-alt0/README.Debian. Please report any successes or failures using these packages.
spfd