Just one mystery envelope today. The mail guy, Nandhram, confirmed that once again, this was from 15.
My Secret Admirer is getting naughty! Or belligerant. A display for a book about Viagra, it reads "It's sweeping the naation. It's changing lives. Is it right for you? Viagra: The Potency Promise." & it is produced by SMP, making the 15th floor all the more likely. Printed in the USA, inside there is the number "425", but it appears to be old ink-- probably written prior to the prank's inception. Also, later in the day, Erin came down to give me some chocolate bars-- if she was the mastermind, wouldn't she have just mailed them? I'm not going to get caught up in reverse psychology ("If she knew that I'd think she would have mailed them, then maybe she'd've done it to lead me off the scent?") because that way lies madness.
(Thanks to Kelly for the evidence photography.)