but these days everyone that can negotiate a bulk-dial agreement with someone and run a radius server can sign up users and make the abuse a bit harder to track ...
Well yes and no. Using a regisrar, people on dialups who want to run mail servers simply cannot do it. The IP space would be owned by the ISP, and the ISP would have to do the mail server registrations for the customer, or SWIP a block (on a dialup, oh boy) and let the customer do the registration themselves. (which would be a legal check as well as technical check). I guess it makes it a lot harder for those customers that setup "not online all the time" mail servers, and that rely on things like ETRN. But mail servers need static IP's, and network operators must know about those customers that need static addresses and if there is a mail server on the end of it. That's a major problem now, mail servers getting online are not tracked.
i do think some sort of smtp-callback would be nice/useful for validation of e-mail addresses. it'll make it so the bounces go to someplace at least instead of Postmaster.
I'm not disputing this at all, but I believe it would take a lot more work to get something set, agreed upon, standardized / RFC'd, the mail server software, etc., than it would to make a registrar type system. Most mail servers pretty much support this already with RBL functions, which would probably be moderately changed. -- Robert Blayzor, BOFH INOC, LLC rblayzor@inoc.net Never trust a program unless you have the source.