Resizing Photos in Apple Mail
Did you know that you can change the size of a photo once you’ve attached it to an email in Apple Mail? This is quite handy, especially if your image is too large to send. You don’t even have to open up iPhoto or Photoshop to do it.
Just drag the image you want to send (from iPhoto or your desktop) into the message area of your New Message window. In the lower right-hand corner where it says Image Size, choose one of the sizes from the drop-down menu. Your photo will automatically be resized. In the lower left-hand corner of the message, the file size will be displayed.
I recommend keeping your email attachments below 10MB when possible. If you need to send larger files, try a file sending service like YouSendIt. http://www.yousendit.com