Hmm, I'm not a big Apple person, but I do use an older Iphone 4S. Can you send the images from within a different app? Rather than just sending it via mail through the standard send options?
My wife uses a large recent Ipad pro for a lot and honestly I don't like a lot of the changes they did from iOS 10 to iOS 11. Maybe I'm in the minority, but I feel like some things were fine and they made it overly complicated. iOS on phones and Ipads shouldn't be like OSX and yet they changed things like adding the dock and what not. Oh well. And my biggest issue is that a lot of the updates are eventually forced and automatic even if you don't want them. My poor old Iphone 4S will probably become unusable as a phone in a year or two since a lot of carriers, I hear, are doing away with 3G networks, but right now I still love it because it literally can't update past iOS 9. Sure it can't run some apps but apart from being slower than more recent smart phones there isn't much it can't do.