There are many tools and ways to scale down images. Fast Resize can do all this at least two steps quicker than most other programs.
Simply drag a few images or even an entire folder containing many images onto the program icon and the folder containing the resized images will open automatically.
After that you could easily drag your images onto an email client. Scaling your images with Fast Resizes default settings will easily allow you to send up to 20 of these images in one email with most service providers.
MAC users can download the package here