If we archive a mail in gmail, is storage saved?
I mean, is the file compressed well?
Gmail can search in archived mail. If it was really compressed, the searching was very hard job. But they can. So I'm very curious about what gmail's archive mean.
Google is probably doing something to save space. Maybe they are indexing and then compressing (older) emails. But your space usage is counted from non-compressed emails.
So in short: archiving do not save your space at all.
Whole point of "Archive" is to move email from inbox. Point is that whatever is in your inbox is something important you should react on, and other things are archived.