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Re: [Asrg] Some data on the validity of MAIL FROM addresses

2003-05-19 07:27:37
At 9:55 PM -0400 5/18/03, Yakov Shafranovich wrote:
They said "no" to 16% of the messages I queried them on. The specific message they used was:

553 VS10-RT Possible forgery or deactivated due to abuse (#5.1.1)

Can you show instances in which they say yes to messages they cannot deliver?

Well they can say yes even though it cannot be delivered - see RFC 2821, section 3.3.

Right.  But the question is--do they?

Fortunately it was easy to test. And the answer is--yes. Yahoo accepts email to addresses that do not exist. I just made up several and got a 250 response to them all. Needless to say, that throws the whole stats thing into complete disarray.

It appears that yahoo is only rejecting messages to addresses that it has already identified as being tagged by spammers. (Thus the 553 rather than 550 response.) A check at a later date would be interesting, since they might have identified more. But the response comes not just for abuse, but also for forgery, so that doesn't prove anything. About the best I can do is mark hosts as to whether or not they normally do immediate rejects, and disregard those hosts that don't.
--
Kee Hinckley
http://www.messagefire.com/          Junk-Free Email Filtering
http://commons.somewhere.com/buzz/   Writings on Technology and Society

I'm not sure which upsets me more: that people are so unwilling to accept
responsibility for their own actions, or that they are so eager to regulate
everyone else's.
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