Letterbox sniffer

Someone who goes around sniffing stranger's letterboxes or bodily parts hoping to get a whiff of pheromones and/or sex.

This is often followed by a lewd or suggestive proposition and often results in violence and/or arrest.

See also crotchsniffer, sexpest and peeping tom

"What's wrong with Jo tonight?"
"She's rampant, sniffing out anything she can."
"Geez, what a letterbox sniffer"