Plan 9 from Bell Labs’s /usr/web/sources/contrib/gabidiaz/root/sys/src/cmd/spf/spf.proto
# Sender Policy Framework for Plan9 386 - sys sys bin - sys sys upas - sys sys spf - sys sys sys - sys sys src - sys sys cmd - sys sys spf - sys sys + - sys sys sys - sys sys man - sys sys 4 - sys sys spf - sys sys
