Look - email comes onto email servers and into users' accounts at all moments of the day. At some point(s) during any given 24 hours, a backup is made of the system (most don't use continuous backup). It is (usually) a snapshot in time. If the user stores their copy of the emails on the server, their entire email account will be backed up by the ISP, day after day. The backup medium is stored for some period of time, after which it is reused and overwriten.
So yes, there is a period of time during which the media is cycling thru the backup rotation scheme where multiple days or weeks of data are available.
the image of the file holding the emails that gets backed up is not the issue - the provider mirrors what is sent to some other folder that is immune for user initiated deletes. that's what google is doing. you delete the mail, but it doesn't matter, they have it mirrored someplace else. you choose to not save a copy of your sent mail, it doesn't matter, they mirror it someplace else.