Mark Sapiro writes:
First, we are not silently dropping this message. We are rejecting it at LMTP time so the sender should be notified.
Sure, but you know how users are about being told that their broken MUAs are spewing crap into the Internet. And most of them will get their mail back and will have no idea how to diagnose what the problem is, let alone repair it.
Then the broader question is should we accept all messages with defects, almost all of which are spam, or only certain defects and which ones.
No (for the reason given), yes, and "it depends". This one I think we can pass through by default. Some lists might want to pass some of the defects that are characteristic of spam. For example, lists for projects developing MUAs in Japan. I regularly got mail with unencoded Japanese in Subject, display names, and occasionally Date at one point in time.
I note that Apple has now released Mail 16 so maybe they've fixed this. My macs are still on Big Sur, so I can't test this.
I have a Mac on Monterey but I haven't switched to it yet, and I'm not a regular user of signed mail and I've never ever used Apple Mail. I'll probably need a bit of handholding to set up a test.
Steve