On 1 February 1991, a new era began for Swiss Post’s predecessor, the PTT. From this date, customers could choose how quickly their letter mail was to be transported. This was the beginning of A Mail and B Mail. At the end of the 1980s, the PTT delivered around 2.5 billion letters a year, and its management believed that this figure would continue to rise. The decade sold claim of “posted today, delivered tomorrow” was in jeopardy. The situation was eased by the introduction of two different transport speeds for postal customers to choose from. The designer of the stamp sought to achieve maximum impact with its small format. He achieved this by reducing the letters “A” and “B” to their inner spaces. The focus on the inner shapes creates a visual link between the two stamps. The warm red and orange tones of the A Mail stamp represent vibrancy and urgency, whereas the B Mail stamp’s cooler blue and green shades convey a sense of calm.