For an explanation of MP and print quality see this article from Hewlett Packard: Is there an easy way to make pictures smaller? The answer is yes, there are many programs available which will resize the picture to make it fit in emails or take up less storage. A program I found and use here at Landmark Group is called "Shrink-O-Matic" which can do one picture or batches of pictures.
When we take pictures of houses we save the pictures, then run them through Shrink-O-Matic to reduce the size by 70% or more. If needed we can still get decent quality prints and we save disk space. There are many other similar programs so I suggest you look around if you have ever found this to be a problem. If you would like to use Shrink-O-Matic, click here to go to thier website and download it.