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Re: Micorsoft's Sender ID Authentication......?
Reputation is a missing element in all sender authentications schemes and will (likely) be solved separately. No approach is perfect, but building closer to a solution is preferred over sitting on our hands and debating, which (historically) seems to be the IETF's approach. - Dan On 6/8/05 12:37 AM, "John Levine" <[email protected]> wrote: >> Yes, there was lots of teeth gnashing and screams of agony allegedly because >> MS refused to license the technology on the terms that folks wanted. MS was >> more than willing to let folks have it at no cost, they just weren't willing >> to give the naysayer everything they wanted, so everyone went home. >> >> (that is, of course, a biased assessment, but not an unfair one) > > There were two problems with the patent license that the MS lawyers > offered. The first was that it reserved to them the right to stop > granting new licenses, thereby pulling the rug out from under anyone > who'd used licensed technology in a product, particularly an open > source product. The said they didn't plan to do that, but MS' lawyers > adamantly refused to change that, so a lot of us concluded that if > they thought the pull out the rug language was important, so did we. > > The second problem was that the license was for two unpublished patent > applications that they described in general terms. When the > applications were published (on a schedule known from the day they > were filed), they turned out to cover vastly more than MS had ever > said. That left a bad taste in a lot of people's mouths. See my blog > entry at http://www.taugh.com/weblog/patapp.html > >> In the mean time, nothing stops MS (and everyone else) from building >> Sender-ID into their MTAs. SPF is a standard and Sender-ID utilized SPF >> records to perform inbound phishing control based on PRA. > > (Danger: operational content ahead.) > > Sender-ID and SPF have serious practical problems. > > The first is that they don't match the way that a lot of mail is > really sent. If all of your mail comes from a single set of servers, > like if you're a big company or an ESP, then SPF or Sender-ID work > reasonably well to tell people which mail is yours. On the other > hand, if you're a university who lets its graduates keep using their > whatever.edu addresses after they graduate and forwards their mail to > them, they doen't work at all. (Other than a legalistic version of > "work" in which you publish a useless SPF record saying that mail > could come from anywhere.) > > This would not be a problem except that SPF has been greatly oversold, > the SPF community has not been particularly diligent in disabusing > people of their misconceptions, and I can promise that the moment > there is a Sender-ID checkbox in Exchange, clueless MCSEs will set it > to reject anything that fails Sender-ID, it'll reject buckets of > normal valid mail, and when people complain, they will insist that the > mail must have been sent wrong because Sender-ID said it was spam. > > Even for fixed senders, Sender-ID is useless against phishing, because > it can only tell you that a message purporting to be from phoop.com > came from a source that is OK for phoop.com, but it cannot tell you > whether phoop.com is someone you want to get mail from. This is a > real problem. For example, I got mail the other day from > customercenter.net purporting to tell me about the status of my MBNA > credit card, with a link to mbnanetaccess.com. Was that a phish? Or > consider mbna-account.com and mbna-accounts.com. One is MBNA, one is > not. Does your MUA know which one is which? Spammers and phishers > can publish SPF records just like anyone else, and Ciphertrust has > said that of the mail they see that passes SPF, there's more spam > than legit mail. > > I am all in favor of sender authentication, if it's real sender > authentication. But Sender-ID isn't. Domainkeys will be better since > it matches mail sending patterns better, but it has the same problem > that a sender that's been authenticated has nothing to do with whether > its mail is desired. > > Shameless plug: over in the anti-spam research group at asrg.sp.am I > sure would like it if people were working on reputation systems to > plug the gaping hole left by all these authentication schemes. > > Regards, > John Levine, [email protected], Primary Perpetrator of "The Internet for > Dummies", > Information Superhighwayman wanna-be, http://www.johnlevine.com, Mayor > "More Wiener schnitzel, please", said Tom, revealingly. -- Daniel Golding Network and Telecommunications Strategies Burton Group