Merlin, Muggles. Yes, like when Muggles tried to have pigeons deliver letters and failed horribly. Mainly because pigeons are terribly dull ...much like Muggles... Owls, however, are not.
And before you ask, no I will not use the post because I am not a Muggle and will not act like one. Owls are much more reliable and one will be on your doorstep tomorrow.