I wrote a console-based mail-client (think "mutt", but with Lua used for all scripting and user-interface work). MessageID headers are often missing, even thou

I wrote a console-based mail-client (think "mutt", but with Lua used for all scripting and user-interface work). MessageID headers are often missing, even though that is "invalid". I've also got thousands of examples of messages with identical MessageID values. (Largely from automated systems that use some trivial/broken template to generate the emails.)