I quite often find people get themselves in trouble when they start deleting things they figure they will never need again. This is ok if it is simply within your own email but if you start doing this from the file explorer, you could quickly find yourself without a computer to use. Therefore it is best to not delete. Since hard drive sizes continue to double, if not quadruple every year,it is very easy to migrate to a newer/larger drive. But getting back to the point at hand, my Gmail account... since I also use Picasa as my photo storage, I have increased my storage to 80gb ($20/year for this through Google--I used to pay that to Flickr but since the integration with Google was there for the same price, not to mention Flickr is Yahoo which is now Microsoft and I'm not a big fan) So I was doing a search through my mail for some tech question I had to answer when I came across dozens, no, HUNDREDS of pages of tech mailings that I "thought" I had deleted... so for the next 20 minutes I found myself doing a search for tech stuff.. the easy one was 'ziff'.. since ziff davis owns most of the tech magazine franchise, that accounted for 390 pages of tech stuff over the last four or five years... the amazing thing was that even after removing all of this (and then going and emptying the trash), I recovered .6 gb of storage!
So, was it worth the time I spent deleting this? Probably not, since you never know what was in some of those mailings, even if I had once already labeled it as trash. What was more disconcerting to me was just why this wasn't being deleted in the first place.. and then I realized a simple toggle switch within the ipad or apple mail that gives you the choice when you press the trash icon, to 'archive' or 'delete' and on one of my devices, it was set to archive.. that being solved, I should not have this problem in the future.