We are experiencing an infestation of European garden snails. They like the wheelie bins we use for garden waste, but are particularly fond of our letterboxes with their paper contents. The contractor who cuts the lawn and trims the hedges left an invoice in my letterbox, the day before bin night, which is the only time I open it because I have a post office box for my mail. There was just enough of the invoice left for me to post it for payment, to our building manager.