I'm tinkering with my DNS entries today and while trying to find out if the
CAA record with
0 issuewild letsencrypt.org was malformed, I got sidetracked into editing templates as discussed here, https://forum.virtualmin.com/t/solved-dns-caa-records/56046/2?u=wnymathguy and then sidetracked again trying to add the MailGun to the SPF area in the templates.
Starting from Virtualmin => System Settings => Server Templates => Edit Server Template => BIND DNS Domain the help bubble from clicking labels Add SPF DNS record?, Additional SPF IPs and hostnames, and Does SPF record cover all senders?} all have the same bad URL. I was looking for help on the syntax of what to write in the Additional SPF IPs and hostnames field to make
mailgun.org part of my system. I clicked the link for http://spf.pobox.com and it was dead. I think the new one is http://www.open-spf.org now.