Today this random guy in a blue and white stripey top put a packet through our door in SE22. It had a beaten up packet and was algae cleaner in this little green egg thing. As he rang the door bell I went to get my keys, came back downstairs just as he'd posted it through the door, I opened the door and he didn't turn back and swiftly walked off. He didn't visit any other houses or flats. Any ideas?!?