Please report dangerous drivers to the police - Roadsafe. Report to plod, not just whinge here.

Write a letter to the Royal Mail as well, keep it very polite and said how disappointed that he put the Royal Mail in a bad light just for driving recklessly.

+1, be objective and polite. You can request a phone call back from the regional manager or someone in a similar position to discuss this further if you want to. It happened to me once (it was a delivery issue not a driving issue, but they should only take this more seriously).

Thanks both, I will do.