Haha! I discovered the identity of the UNKNOWN SENDER—after he —yes, because it is a "he"—sent ORANGE (see PROY#29), with (N.B.) possibly even LESS CUES! But, as my Schwiegervater was detective, I know how to find cues: under the shower! So, I took a shower at Christmas!
KulturBarbarin die ich bin!!! Hatte ich die Venus von Arheilgen nicht erkennt... Shame on me!