DynDNS has announced that their MailHop service will no longer generate NDRs (Non-Delivery Reports, commonly known as bounce messages). They point out that this is technically a violation of RFC 2821 section 3.7. I’d observe that it violates section 3.6 of RFC 821, which is the current SMTP standard, as RFC 2821 is still a proposed standard.
The rationale for not generating bounce messages is that spammers forge the from address of mail messages, and when spam is undeliverable the bounce messages thus clog the mailboxes of innocent third parties (“blow back”) and waste bandwidth. I modified one of my mail servers (running qmail) to disable generation of bounce messages some months back, in response to repeated complaints by the recipients of such bounce messages. Even though doing this does violate the RFCs, it is a benefit to all legitimate email users, and DynDNS should be commended for doing it. I hope that other major email providers will follow suit.
When RFC 2821 is next revised, it should be change to require MTAs to generate bounce messages if and only if the origin of the email can be authenticated (e.g., by DomainKeys).
Thats great. My sons email is constantly full of these messages. I just checked and he had 300 of them. I guess I should be glad that he is the only one at our domain who gets them. I have tripple checked that my server is not sending the spam.
One day I actualy traced several of them and sent email to the offending mail server administators. I never heard anything back. One of them was actualy owned by the US Navy.