DynDNS Drops Non-Delivery Reports

Posted by kdawson on Friday August 24, 2007 @08:01AM from the one-less-spam-vector dept.

jetkins writes "In an email to subscribers, DynDNS announced that they will no longer deliver locally generated non-delivery reports (NDRs) from any MailHop systems. MailHop is a multi-faceted service offering in- and outbound relay services, spam and virus filtering, and store-and-forward buffering. DynDNS makes it clear that they are aware that this goes against RFC 2821 Section 3.7, but explains that in their opinion the increase in spam volume, and the use of NDRs as a spam vector, means that the value of NDRs is now far outweighed by their potential for harm. (DynDNS also points to the far greater reliability of email systems now than when the RFC was approved.) The company notes that other ISPs have quietly dropped RFC 2821-compliant NDRs. Will their public move start a flood (mutiny) of ISPs following suit? Should they have made efforts to have the standard changed instead of defying it?"

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Re:Finally, a service provider with a clue... by jetkins · 2007-08-24 08:55 · Score: 5, Informative

A large proportion of Joe Jobs are made possible by lame endpoint SMTP servers which accept incoming mail, close the connection, then check to see if the recipient is valid, and generate an NDR to the address specified in the headers, which are too easily forged.
A properly-configured endpoint server should check addressee validity during the SMTP exchange, and reject the transfer before it even gets into the system, so the spammer's attempt goes nowhere and "Joe" doesn't get an unwarranted NDR.
Of course that doesn't help proxy providers like DynDNS, unless they have some way of authenticating their clients' valid addresses in real time via a direct connection or regular updates.