It is wise to compress images from your digital camera BEFORE you send them. And just because you have superduper high resolution camera, it doesn’t suddenly make you Ansel Adams. You remain you, with a high resolution crappy snapshot.
It is also wise to make sure the pictures would be of any interest to the person that you accidentally emailed them to.
Funky girl making wacky face in front of a hot dog stand, at 3mb, well, that just sucks. I don’t even know who funky girl is, or why I should care.