Marc S. Glasser
Thank you, sir. I just sent the same message I'd sent a month ago, from the same e-address, and got the bounce immediately:
<<< 500 This message has been flagged as spam. 554 5.5.0 Remote protocol error
Not as good as having it accepted for moderation, but at least it provides closure for the sender. With luck, the issue won't come up very often over the ensuing months.
Thanks again for listening and responding!