[MM3-users] Any known cases of "non-members" who aren't explicitly allowed to send to the list with a default rule of "discard" on a list getting through?

We just noticed an oddness in a client's system.

Someone sent to a members-only list and it 'got past' moderation controls.  The list is set to not allow non-members to send to the list, but somehow it got through the default rule of "discard (no notification)" for a non-member and got to the list.

The only oddness I can tell is that there was an emoji (unicode) in the subject line but as I understand how Mailman works, this should NOT have impacted anything, as the sender filter bits happen earlier in message processing.

Has *anyone* seen any cases like this before?  If this is repeatable or a known issue, it deserves a CVE security bug because this is a **severe** problem.