Why would a famous composer mail the Berlin tramway company a sheet of paper on which he had drawn seven concentric circles (the outermost red, two others blue and one yellow), all intersected by twelve radial lines? Arnold Schoenberg was annoyed.
Every time a passenger, say a composer, changed trains in 1927 Berlin (one year before several transportation companies would merge to form the Berliner Verkehrs-AG), she or he had to buy a new ticket. Schoenberg was fed up enough to devise a solution: a pre-purchased ticket valid for all lines and directions for a certain time. The conductor would simply mark the day (circle) and time (line, as on a clock) when the passenger first got on.
If, now, you want replies to your emails to take a different tram in a different direction, get them transfer tickets in Gmail:
›› Want to receive replies to your emails at an address different from that used for sending? In Gmail, you can set up Reply-To addresses per account — and easily.