Think about the world 30 years ago, before internet was a part of everybody life. Think of someone walking out to the letterbox, taking out a letter, review it and put it back, then next one and the same thing until finally look at a mail he wanted to bring inside.
Then 30 minutes later the same guy comes out again, following the same procedure. He would have been considered insane. Probably not a bad assessment. But that’s exactly the same behavior that’s very common today, and nobody consider it weird. Well, almost nobody.
You should handle your electronic mailbox the same way as your old letterbox outside. Once taking stuff from there, never put it back.
Because although you have a lot of search opportunities in your mailbox you will never be able to have the control and overview over it if you have thousands of mails there. Sooner or later you will miss something.