27: Obviously Forged

60 Seconds of WIP · Dec 28, 2023 · 1m

Here’s another chunk from Run Your Own Mail Server.

Ideally, sysadmins want all the messages from their domain to conform to the highest possible standards. They intend to sign everything with DKIM, and publish SPF records that contain every host that might possibly send mail. Anything that doesn’t have perfect alignment is obviously forged and should be unilaterally discarded. Anyone who’s worked in computing more than a week understands that they missed something, though. Some critical system sends mail from its own hostname rather than the domain, or there’s that weird host system…