Gmail icon makes no sense.

So I was on Android Police, and several of the related articles were about gmail and had the gmail icon as their article picture. I don't know why I lingered so long, but it got me thinking just what it was supposed to *be*.

The gmail service icon makes sense. it's an envelope, it makes an M for mail.

Gmail-logo_medium

via socialprestige.files.wordpress.com


Then I look at the android app icon....it's an envelope....but there's just a big red M on a piece of paper inside of it? How does that make any sense? Is it an envelope inside an envelope?

Gmail-icon_medium

via icons.iconarchive.com

Am I missing something or does this really just not represent an envelope but simply a red M in another envelope?