Experimentalism, Safety Cultures, Technology and Global Health
I love biking in the snow. The landscape and trails change so dramatically in such a short time, and its great to ride snow-covered trails that you’ve already ridden in rain, wind, sun, baking heat, and whatever else we put up with (enjoy).
On this occasion, the drifts were a bit bigger than I’d expected, but it was still a great ride.
An SPF record is a DNS TXT record (like A records and MX records) that indicates to receiving mail servers whether an email has come from a server that is “allowed” to send email from that domain. I.e. it’s a check that should prevent spammers impersonating your domain. It does rely on the receiving server actually doing the check, which not all do, so it’s not by any means fool proof, but it should help prevent mass email from your organisation to customers being flagged as potential spam.
Below is an example SPF record for capitalfmarena.com:
(this is in the public domain – you can look up an organisation’s SPF record by using online SPF checkers)
“v=spf1 ip4:93.174.143.18 mx a:service69.mimecast.com mx a:service70.mimecast.com a:capitalfmarena.com -all”
V=spf1 specifies the type of record this is. (SPF)
Ip4: pass if the IP senders IP address matches the addresses we send mail from.
mx a: pass if sender’s IP matches an ‘MX’ record in the domain
a: pass if Sender’s IP matches an ‘A’ record in the domain
The –all indicates that all other senders fail the spf test. (+all would mean anyone can send mail.)
(~all was used when spf was still being implemented, and is a soft fail, but shouldn’t really be used any longer other than when you’re transitioning between mail hosts or something)
Mechanisms are tested in order and any match will pass the email. A non-match results in a neutral state, until it gets to the end of the string where the –all mechanism will fail it.
I recently took a week off work to go biking, snowboarding, climbing, and hiking and stuff. Part of the trip included a visit to Wales to stay at penmachno after riding llandegla. I was going to ride penmachno the following day, but the weather was dreadful, so I walked halfway up snowdon instead 🙂
Sherwood pines is a nice little place to ride – the main trail is quite short, but is pretty much 100% twisty fast singletrack, and you can get a couple of loops done in two hours. I went for a ride there recently in the heavy snow, and I was so lucky to have the trail to myself. The snow was fresh – no foot prints or tyre tracks, and it was deathly silent in the woods with the snow falling heavily. Absolutely brilliant, although I couldn’t feel my feet after 15 minutes or so…
