I just made an observation how development of online applications and the wide use of fast internet services has made some attributes of an e-mail obsolete.

Gmail doesn’t have it visible anymore, but most desktop applications do – do you know what attribute of an e-mail message I’m talking about?

Size.

On desktop computers, it’s become obsolete – in mobile devices it still matters. For a while. When certain metrics are becoming diminishingly unnecessary, you should consider them as unnecessary to begin with. Measuring them is of no value to the end user and therefore you shouldn’t harass the user with the information.