Jut to add: they don't get delivered at anywhere near the speed of light. This is a fallacy.
To get around, like any other traffic on the internet, they get routed through various servers. These servers are probably routing other traffic too, so may take a second to get to your email in its queue.
However, 'hours' isn't quite right. This suggests something is a little wrong.
I can send an email to myself, or from someone else, and get it within 10 seconds or so. Not too bad.