I have at least three mp3's that were ripped like 8 years ago that I've sent to myself over the past couple years (2009 is most recent). They are all there and still good, and artists that I'd assume would be taken down if this was true.

You can check if you have any by searching, adding ".mp3" to required words and clicking check attachments (I also added from me to me)

I call BS. There are just too many legit reasons of having copyrighted mp3's in your mail.

No chance they did this, aside from the obvious implications and backlash they would suffer.... why would they remove files that aren't publicly indexed or shared and can't be found to be DMCA'd.

I am pretty sure that Google Music allows you to upload any mp3 you like which makes me think that they would start there and not your email.

Seems implausible. For one obvious example, any web store that sends you MP3s you've purchased via e-mail (I've used a few) would now no longer function because GMail would delete the MP3s before you could even download them to listen to them.

Difficult to confirm or disprove without a few examples (artist name, track name) that people can test with their own legit (copyrighted) MP3s.

my mp3s i purchased from amazon, that i emailed myself are still there.