In order to get your email looking beautiful, some of your products' images might need to be resized.
You will find the image resize option in the Product block, Image block and Collection block.
When you picture is already in you block, simply click on "Resize" and modify it depending on your needs.
To keep your original picture's dimension, we recommend that you keep the dimensions locked.
Changing the image size might also help you get your products to align when using two/three columns product/images
To do so, simply change one of your images' height to match the other's.