> > I administer a mail gateway processing upwards of 7,000 messages per > > day, and unabashedly can confirm we trash more than 4,000 of these > > per day unread and without providing notifications as to why. This > > is common practice throughout Government, corporate's and business, > > the academy and most other large organisations and institutions. > > Can anyone suggest a good quotable reference for the fact that this > kind of thing is common practice? > > Thanks in advance! > > Greetings, > Norbert.
My organization does multi-stage spam and virus filtering for a variety of agencies, educational institutions, and non-profits. We process around a half-million incoming e-mails a day, and approximately 3/4 of them are filtered out as spam or as virus-infected. Our filtering statistics are publicly available at http://www.wvnet.edu/getmstat.php. Regarding the issue of sender notification, a good overview of a rigorous approach to multi-stage filtering practices is available at http://www.spamhaus.org/effective_filtering.html. As this illustrates, the roughly 80% of spam that is detected in the first stage of multi-stage filtering will result in non-delivery notification to the sender's mail server, which then MAY notify the sender. The other 20% of spam, as well as any viruses, will be detected at later stages. These later stages require inspection of the message content, so the e-mails must be received from the sending mail server before processing can begin. However, as soon as the receiving server accepts an e-mail, the sending server considers its role in delivery to be complete, and it deletes the messages from its outbound queues and disconnects. Some e-mails accepted by the receiving server will subsequently be identified as spam or as infected, and these messages will then be deleted or quarantined, depending on the receivers' practices. However, because the dialog with the sending server has already completed at that point, non-delivery notification is rarely attempted for mail that is intercepted at these later stages. Moreover, most spam and virtually all viruses are sent from either zombies or spoofed addresses. Sending non-delivery reports for mail intercepted at these later filtering stages would add to the general clutter on the Internet and would only confound most recipients of the reports, who are generally either innocent or at least unaware of having sent the offending messages. - Ed Ward _______________________________________________ DIGITALDIVIDE mailing list DIGITALDIVIDE@mailman.edc.org http://mailman.edc.org/mailman/listinfo/digitaldivide To unsubscribe, send a message to [EMAIL PROTECTED] with the word UNSUBSCRIBE in the body of the message.
