I wrote:
IN A 198.144.195.186 IN MX 10 linuxmafia.com. IN HINFO P3/500 Linux-v.2.4.24 IN TXT "v=spf1 ipv4:198.144.195.186 -all"
^^^^
LOC 37 25 53.825 N 122 11 52.128 W 15m
_And_, I screwed this up -- having arrogantly not bothered to double-check SPF TXT RR syntax before writing the RHS string, and instead doing it from memory. Correct version:
IN TXT "v=spf1 ip4:198.144.195.186 -all"
Note (correct) 'ip4', vice (incorrect) 'ipv4'.
That'll teach me to skip the all-important 'verify your work' step. Fortunately, the RR wasn't incorrect (invalid syntax) for very long.
Useful tool: Send an e-mail to check-auth@verifier.port25.com and you will receive a reply containing the results of an SPF check.
The similar tool that used to be available at spf-test@openspf.net has been discontinued.