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Re: Clueless anti-virus products/vendors (was Re: Sober)

  • From: Douglas Otis
  • Date: Tue Dec 06 19:27:43 2005

On Dec 6, 2005, at 2:15 PM, Todd Vierling wrote:
On Tue, 6 Dec 2005, Douglas Otis wrote:

Holding at the data phase does usually avoid the need for a DSN, but this
technique may require some added (less than elegant) operations depending upon
where the scan engine exists within the email stream.
Not my problem. I don't need or want, and should not be hammered with, virus "warnings" sent to forged addresses -- ever. They are unsolicited (I didn't request it, and definitely don't want it), bulk (automated upon receipt of viruses by the offending server), e- mail... thus UBE.
I know of no cases where a malware related DSN would be generated by our products, nevertheless, DSNs are not Unsolicited Bulk Email.

Generated virus "warnings" must not go to a known forged sender, or to a sender for which the forgery status is unknown. If you cannot *guarantee* that the address in MAIL FROM:<> is correct, and cannot reject at SMTP time, your only options are to quarantine, discard, or allow delivery. Do not send a DSN; do not pass Go; do not collect US$200.
Not all email is rejected within the SMTP session. You are changing requirements for recipients that scan incoming messages for malware. Fault them for returning content or not including a null bounce- address. No one can guarantee an email-address within the bounce- address is valid, furthermore a DSN could be desired even for cases where an authorization scheme fails. Why create corner cases?

There is always BATV to clean-up spoofed bounce-addresses in the meantime.
And other methods (DK, SPF, SID, choose your poison). However, if the server cannot verify that the MAIL FROM:<> is not forged with reasonable certainty, the server should not send a DSN, period. Otherwise, it's a direct contributor to the UBE problem.
DomainKeys and Sender-ID can not validate the bounce-address or the DSN. Even with an SPF failure, a DSN should still be sent, as SPF fails in several scenarios, and false positives are never 0%. BATV offers a unilateral option that can effectively discard spoofed bounce-addresses. When the AV software provides the DSN with a null bounce-address, BATV works as advertised.