pyspf doesn't like it when an SPF record contains invalid characters, and this causes pypolicyd-spf to crash and reject mail rather than return a PermError as it should. Scott Kitterman has fixed this in Ubuntu (see URL), with a patch here: http://launchpadlibrarian.net/107955769/pyspf_2.0.7-1_2.0.7-1ubuntu0.1.diff.gz
05 Apr 2013; Ian Delaney <idella4@gentoo.org> +files/pyspf-2.0.7-catch_unicode.patch, +pyspf-2.0.7-r1.ebuild: Patch acquired from bugs.launchpad.net/pypolicyd-spf/+bug/832480, fixes Bug #463892