Checking SPF records with python

August 04, 2022

A short post on checking email SPF records (with python).

Install pyspf and py3dns.

Run python -m spf <> and record the output. Alternatively you can use nslookup -q=TXT <domain> and look for one that starts with v=spf1.

Next validate the senders ip by running python -m spf "<spf output>" <the.ipv4.addr.val> <> a.

You should see result: ('pass', 250, 'sender SPF authorized') mx!

If the ip is wrong or SPF is not configured correctly, you'll see something like result: ('fail', 550, 'SPF fail - not authorized') -all.

There also a simple web page to do this here and wikipedia has a article explaning SPF.