The fact that the RFCs do not require a msg-id should stop SA from creating a rule that enforces a *non-requirement*.
No it shouldn't. SA creates rules that indicate spammishness. The rules are run against the corpus and the ones that get the most spam/least ham get the highest scores.
And, for the purposes of 99% of users in 99% of cases, a SHOULD in a RFC is just as important as a MUST. A SHOULD only exists to allow some flexibility in extremely limited and extremely specialized cases. Not to simply ignore because you feel like it.
-- I listen to the wind, to the wind of my soul
