I'm having an issue when I send any picture (via iMessage) to one person in particular. Whenever I try to send to them it says it's been delivered, then after a few minutes it says the message failed to send. I've tried sending him a picture from my wife's phone and it works fine, and I can send to other people without issue. I've tried resetting my network settings and that didn't return an error message but he also didn't get the picture. Then after I tried again I'm having the same problem. Everything I've seemed to find on this issue is either it works for everybody or it doesn't work for anybody, but not just one person in particular. This has been happening for maybe a week with this person. I'm on iOS 9.3.2 on a 6s+.