What size is your graphic? If its very large then it will take some time. Try reducing the size, though if you must send it full size, why not just send a much smaller one in the email, a thumbnail for example, with it linked to your much larger one on your site. Click on link, voila, full size.
If on the other hand you are wanting not to merely show the image but send it, well zipping it (compressing it) is the way to go. You will prob find it then sends no problem if apart from images, your mail is working ok.