Images look different after email

So i downloaded some images to my computer, previewed them, and then tried to send them to someone via email. The images look fine on my desktop, and they look fine on the other person's screen, but they look wrong on a phone screen when viewing the email on an iPhone. I'm sending around 30 images, and the first four almost look desaturated, but the rest look perfectly fine. Why would some images look fine on a desktop but look wrong on a phone? I've never had this issue before.