On Fri, Apr 15, 2022 at 04:30:19PM -0600, @lbutlr wrote: > However, it is *very* common for a BBC email to have a To header with > no email address in it at all,
This violates RFC5322 and earlier versions. The "To:" header must contain at least one address (or group). https://datatracker.ietf.org/doc/html/rfc5322#section-3.4 https://datatracker.ietf.org/doc/html/rfc5322#section-3.6.3 -- Viktor.