I don't use Mail.
Like most users, I did initially used it considering how simple it looked, but then soon realise how functionally handicapped it was compared to 3rd party apps.
Most mail apps nowadays, preview the most recent conversation, so you don't even have to open the email to know the latest status. If your reply to an email happens to be the latest in the thread, it can be viewed in the preview. On tapping an email, the entire conversation can be viewed, including the sent emails. Coming to the default Mail app, the conversation list does not even include sent messages. To view the sent messages, you have to go search for it in the sent items folder, a hassle, esp when you are short of time and you want to view the full email trail. Including both incoming and sent emails in the conversation is a basic feature in most 3rd party apps. Just an example of where Mail is compared to other apps.