I tried something like that a couple years ago, in part to be able to hide an account's real e-mail and just be able to use (you)@cabl.com. Go to the Private Message screen and there's a link there, "View Incoming Email". It only works for a few people and was never widely implemented. If I do something like that then I have to make sure it works and is reliable all the time for tens of thousands of accounts, and be able to deal with the management issues. It came down to: do I want to deal with thousands of people upset because some problem happened and they can't access mail? Would I want that responsibility and for what benefit? It never got to the point where I was comfortable with that. Instead, the original problem was solved by hiding e-mail addresses with the {Click for E-mail} thing.
Still, I probably will do something along those lines someday, if only for the novelty aspect. A long time ago I registered some domains like CableSplicer.com, CableDog.com, etc. for that purpose. It might have to be a direct forwarding to another e-mail instead of an endpoint, to simplify things. If there's interest then bug me enough and I might think more about it.
Right now it's hard work just making sure the mail works as it is.
