Apple's Email App does a bad job of showing "Threaded Conversations"
If you've ever used Gmail, you're already familiar with "Threaded Email", which means that when you view any given email. you see all subsequent replies in chronological order, with the newest at the bottom.
Apple recently added what they consider Threaded Email to their iOS Mail App, but it's missing something very important. Emails you sent as replies are not included as part of the thread. What you end up with is only half a conversation.
By contrast, Google's Gmail App is fully threaded and it's easy to follow each conversation, which isn't surprising because Google was the first major email platform to support it.