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.
Website: https://www.picture-instruments.com
Download: FastResize2.0.0Bitsdujour-September2020.dmg – FastResize2.0.0Bitsdujour-September2020.exe
Download: FastResize-2.0.0-Win.zip – mirror
Download: FastResize-2.0.0-Mac.zip – mirror
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.