Hey Chef! When I resize my pictures I use photoshop or paint and change the height and width by pixels. The reason your pictures are so big when they come out on email is because they height and width are huge. So what you can do for example is if your picture is 1650 x 1080, change it to 800 x 600 or something along those lines in photoshop or paint if you have them.
If you want an easier way then you can go here
http://www.picresize.com/. Once there you can select your picture and change many features. You can just say make it 75% or 50% smaller or you can put in the desired height and width in pixels. You can also change some effects if you want idk.
