Slashdot Mirror
Novel Method for Universal Email Authentication
MKaplan writes "Most spam is sent using spoofed domains. Email authentication schemes such as SPF attempt to foil spoofing by having domain administrators publish a list of their approved outgoing mail servers. SPF is sharply limited by incomplete domain participation and failure to authenticate forwarded email. A paper describes a novel method to rapidly generate a near-perfect global SPF database independent of the participation of domain administrators. A single email from an unauthenticated domain is bounced and then resent — this previously unauthenticated domain and the server listed in the return path of the resent bounce are entered into a globally accessible database. All future emails sent from this domain via this server will be authenticated after checking this new database. Mechanisms to authenticate forwarded email and to nullify subversion of this anti-spam system are also described."
So what happens when you receive an email from a big site like Sympatico, Hotmail, or any number of other places that have farms of SMTP servers, where your message isn't guaranteed to be resent from the same IP?
This also requires users to install software to use effectively, and features CAPTCHAs which are a usability nightmare and not nearly as impregnable as the author thinks.
All that effort instead of just adding a TXT record to their domains.
No, not at all. If you don't want to read the article, just keep guessing how it works, and we'll let you know if you are getting warm.
...but this had to be posted.
Your post advocates a
(X) technical ( ) legislative ( ) market-based ( ) vigilante
approach to fighting spam. Your idea will not work. Here is why it won't work. (One or more of the following may apply to your particular idea, and it may have other flaws which used to vary from state to state before a bad federal law was passed.)
( ) Spammers can easily use it to harvest email addresses
( ) Mailing lists and other legitimate email uses would be affected
( ) No one will be able to find the guy or collect the money
( ) It is defenseless against brute force attacks
(X) It will stop spam for two weeks and then we'll be stuck with it
( ) Users of email will not put up with it
( ) Microsoft will not put up with it
( ) The police will not put up with it
( ) Requires too much cooperation from spammers
( ) Requires immediate total cooperation from everybody at once
( ) Many email users cannot afford to lose business or alienate potential employers
( ) Spammers don't care about invalid addresses in their lists
( ) Anyone could anonymously destroy anyone else's career or business
Specifically, your plan fails to account for
( ) Laws expressly prohibiting it
(X) Lack of centrally controlling authority for email
( ) Open relays in foreign countries
( ) Ease of searching tiny alphanumeric address space of all email addresses
( ) Asshats
( ) Jurisdictional problems
( ) Unpopularity of weird new taxes
( ) Public reluctance to accept weird new forms of money
( ) Huge existing software investment in SMTP
( ) Susceptibility of protocols other than SMTP to attack
( ) Willingness of users to install OS patches received by email
( ) Armies of worm riddled broadband-connected Windows boxes
(X) Eternal arms race involved in all filtering approaches
( ) Extreme profitability of spam
( ) Joe jobs and/or identity theft
( ) Technically illiterate politicians
( ) Extreme stupidity on the part of people who do business with spammers
( ) Dishonesty on the part of spammers themselves
( ) Bandwidth costs that are unaffected by client filtering
( ) Outlook
and the following philosophical objections may also apply:
(X) Ideas similar to yours are easy to come up with, yet none have ever been shown practical
( ) Any scheme based on opt-out is unacceptable
( ) SMTP headers should not be the subject of legislation
(X) Blacklists suck
(X) Whitelists suck
( ) We should be able to talk about Viagra without being censored
( ) Countermeasures should not involve wire fraud or credit card fraud
( ) Countermeasures should not involve sabotage of public networks
( ) Countermeasures must work if phased in gradually
( ) Sending email should be free
(X) Why should we have to trust you and your servers?
( ) Incompatiblity with open source or open source licenses
( ) Feel-good measures do nothing to solve the problem
( ) Temporary/one-time email addresses are cumbersome
( ) I don't want the government reading my email
( ) Killing them that way is not slow and painful enough
Furthermore, this is what I think about you:
(X) Sorry dude, but I don't think it would work.
( ) This is a stupid idea, and you're a stupid person for suggesting it.
( ) Nice try, assh0le! I'm going to find out where you live and burn your house down!
The proposed scheme ignores one thing: the majority of bounce messages today are false bounces caused by spammer joe-jobs, therefore they themselves get flagged as spam and deleted/ignored. In addition, it also increases the annoyance of greylist authentication schemes, since a spammer forging my address in the From field will cause every host participating in this scheme to send me a verification e-mail for a message I didn't send which I'll have to deal with. The proposed scheme makes a very fundamental mistake: assuming that you can trust the sender's address in a message to be the true sender's address. You can do that only after you've determined the message is authentic and not spam, at which point you don't need this scheme anymore.
Your post advocates a
(*) technical ( ) legislative ( ) market-based ( ) vigilante
approach to fighting spam. Your idea will not work. Here is why it won't work. (One or more of the following may apply to your particular idea, and it may have other flaws which used to vary from state to state before a bad federal law was passed.)
( ) Spammers can easily use it to harvest email addresses
(*) Mailing lists and other legitimate email uses would be affected
( ) No one will be able to find the guy or collect the money
( ) It is defenseless against brute force attacks
( ) It will stop spam for two weeks and then we'll be stuck with it
(*) Users of email will not put up with it
( ) Microsoft will not put up with it
( ) The police will not put up with it
( ) Requires too much cooperation from spammers
( ) Requires immediate total cooperation from everybody at once
(*) Many email users cannot afford to lose business or alienate potential employers
( ) Spammers don't care about invalid addresses in their lists
( ) Anyone could anonymously destroy anyone else's career or business
Specifically, your plan fails to account for
( ) Laws expressly prohibiting it
( ) Lack of centrally controlling authority for email
(*) Open relays in foreign countries
(*) Features in MTA software that can be disabled, such as MDNs
( ) Ease of searching tiny alphanumeric address space of all email addresses
( ) Asshats
( ) Jurisdictional problems
( ) Unpopularity of weird new taxes
( ) Public reluctance to accept weird new forms of money
( ) Huge existing software investment in SMTP
( ) Susceptibility of protocols other than SMTP to attack
( ) Willingness of users to install OS patches received by email
(*) Armies of worm riddled broadband-connected Windows boxes
( ) Eternal arms race involved in all filtering approaches
( ) Extreme profitability of spam
(*) Joe jobs and/or identity theft
( ) Technically illiterate politicians
( ) Extreme stupidity on the part of people who do business with spammers
(*) Dishonesty on the part of spammers themselves
(*) Bandwidth costs that are unaffected by client filtering
( ) Outlook
and the following philosophical objections may also apply:
(*) Ideas similar to yours are easy to come up with, yet none have ever been shown practical
( ) Any scheme based on opt-out is unacceptable
( ) SMTP headers should not be the subject of legislation
( ) Blacklists suck
( ) Whitelists suck
( ) We should be able to talk about Viagra without being censored
( ) Countermeasures should not involve wire fraud or credit card fraud
( ) Countermeasures should not involve sabotage of public networks
( ) Countermeasures must work if phased in gradually
( ) Sending email should be free
( ) Why should we have to trust you and your servers?
( ) Incompatiblity with open source or open source licenses
(*) Feel-good measures do nothing to solve the problem
( ) Temporary/one-time email addresses are cumbersome
( ) I don't want the government reading my email
( ) Killing them that way is not slow and painful enough
Furthermore, this is what I think about you:
(*) Sorry dude, but I don't think it would work.
( ) This is a stupid idea, and you're a stupid person for suggesting it.
( ) Nice try, assh0le! I'm going to find out where you live and burn your house down!
I didn't spend too much time looking through the options, so go easy if I got it wrong. Will that do?
Resistance is futile. Reactance buggers it up.
I don't know about the GP, but for me greylisting is very effective. I have a personal domain for my wife and myself. I have a catchall mail address.
Here are some stats for part of last week:
Start Date 23/09/07 04:02
End Date 28/09/07 17:00
5.54 days
Total spam: 4624
Spam blocked with greylisting: 4478 (96.8%)
spam via backup MX: 69 (1.5%)
spam retried (got past greylisting): 77 (1.7%)
Total through to end user: 146
Identified as spam (SpamAssassin): 123 (84.2%)
backup MX marked as spam: 50 (72.5%)
direct marked as spam: 72 (93.5%)
Total to end user not marked as spam: 23 (0.5%)
NB. Up until about a month ago, ~25% of SPAM came via my backup MX, which doesn't have greylisting. I don't know why it dropped, but I'm happy it did.
Ever stop to think