Re: [apps-discuss] I-D Action: draft-ietf-appsawg-malformed-mail-02.txt

["John Levine" <[e-mail]>]

>> I'd also suggest that the draft emphasize that many kinds of errors are
>> strong indicators that a message is spam or contains malware, ...

>I certainly agree with the latter.  I think the former is a little more
>dangerous, because there are lots of errors that are innocent or
>ignorant rather than attempts to deceive.  That doesn't make them right,
>but it does mean drastic measures can have unwanted side effects, just
>like assuming a failed SPF check or DKIM signature validation is
>automatically a sign of foul play.

Depends on the error.  There are highly accurate blacklists that work
by looking for technical errors in spam that are characteristic of
botware.  I certainly am not proposing that you say what the bot
signatures are, just that certain kinds of errors strongly suggest
that it's a message best rejected or discarded.

>Many deviations from what [MAIL] specifies are considered by some
>receivers to be strong indications that the message is undesirable,
>i.e., is spam or contains malware.  Such receivers quickly decide that
>the best handling choice is simply to reject or discard the message. 

Yes.

>This means malformations caused by innocent misunderstandings or
>ignorance of proper syntax can cause messages with no ill intent also to
>fail to be delivered.

Maybe, depends on the filter.  See above.

>Senders that want to ensure message delivery are best advised to adhere
>strictly to [MAIL], as well as observe other industry best practices
>such as may be published either by the IETF or independently from time
>to time.

Yes

R's,
John