We do an N+1 for OS's. so you can only be 1 major OS behind otherwise your email gets blocked. We do stretch that some when new os's come out like IOS 13. It'll be probably a couple more months before we tell users we only support 12 and up. Which then we will change the compliance policy, announce the change, upgrade devices if need be, for personal devices.....it does come down to ' security' if your model can't update. ' Sorry, if you want email you need a new phone.' Somehow this hasn't blown up in our face yet! 🙂