North American Network Operators Group

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Re: SMTP store and forward requires DSN for integrity (was Re:Cluelessanti-virus )

  • From: Matthew Sullivan
  • Date: Sat Dec 10 06:55:51 2005

Robert, sorry I missed the full conversation, and don't have time to read the whole thread, but based on your mail alone a few words of agreement...

Please remember people..

RFC 2821 states explicitly that once the receiving server has issued a 250 Ok to the end-of-data command, the receiving server has accepted responsibility for either delivering the message or notifying the sender that it has been unable to deliver. RFC2821 also says that a message MUST NOT be dropped for trivial reasons such as lack of storage space for the message. To that end is a detected virus/trajan/malware/phishing scam etc... a trivial reason to drop the message?

Personally I believe that not trivial means not unless the entire server crashes and disks fry etc... To that end I am a firm believer that malware messages SHOULD BE rejected at the end of the data command (which is why I have gone to great lengths to ensure this happens at $employer, and at SORBS).. Failure to have the resources available to perform the virus scanning will result in the messages being delivered to the recipient as a broken message (attachment stripped).

There is certainly NO EXCUSE for ANYONE to bounce virus warning messages to ANY user whether local or remote, particularly when the anti virus software will identify the virus and the virus is KNOWN to forge the sender address.

As such anyone bouncing large numbers virus warning messages are game for having their servers blocked, and I will not apologise to anyone getting caught by a SORBS automated spamtrap getting a virus warning message (though I will remove them promptly when notified of such an entry).