Mail attachments (pics) too small?

Hi guys / gals.

I've noticed something very strange and annoying about the mail.app -

When I attach an image and email it to somebody, they get a downsized / smaller file and NOT the original!! I've looked under "preferences" and can't find anything relating to this - I've also tried searching on here + googling - perhaps

I'm either 1) searching for the wrong terms 2) attaching images using a bad method? 3) both!

My method is to drag and drop an image into an open (new) message.... I'm pretty sure that using the attachments dialogue has exactly the same effect though....