I have Gmail and for emails that I might want to see again, (their Black Fri sale, but not the rest of the year,) I create a filter that just automatically deletes them. Then close to Black Fri, I can check my deleted mail or take the filter off of their emails for a while andthey are back in my Inbox.
I prefer Gmail over Hotmail or Yahoo. With those accounts I get a LOT of SPAM that isn't automatically filtered out by their email filters. OR there's a lot of SPAM that is filtered and is cluttering up that folder.
Gmail's filters are a lot better. I almost never get anything in the SPAM folder as I think they pte-filter stuff so well, it never even makes it to the SPAM folder. When I get the occasional 1-2 emails, I can go and take a look at them before fully deleting the folder. So, I can catch the ocassional email, right away, that shouldn't be in there. They are usually the questionable ones by Gmail, so they put it in that folder, but let me see them, so I can make the final decision. My Gmail SPAM folder is almost always empty.