How fast mail travels from one point to another - ie from you to the recipient - depends on many different things. The speed of your internet connection for example, the load on the servers it passes on it's way to the recipient and of course the available bandwith etc. It's pretty much like highway traffic: At peak times there might be traffic jams and everything moves slower and at certain times, mail might just zip through the system. There isn't really anything you can do. But be assured: The mail providers do everything they can to ensure a timely delivery of mail.
