Does OpenBSD provide an ISO image available for download?
You can't. The official OpenBSD CD-ROM layout is copyright Theo de Raadt, as an incentive for people to buy the CD set.
Note that only the layout is copyrighted, OpenBSD itself is free. Nothing precludes someone else to just grab OpenBSD and make their own CD. [emphasis mine]
So I could produce a functionally identical CD and even sell it, but if I stuck the original artwork on it, I'd be in violation.
Most of my MX records point at a CNAME,
Doesn't that ever cause you problems? MX records must not point to a CNAME RR.
this policy is subject to change at any time, with or without notice to you.
To err is human, to moo bovine.