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Re: SMTP and DKIM/POLICY Rejection Handling [OFF LIST]

2009-10-21 20:00:34

Hector Santos wrote:

I think ideally I could see a rejection code that maybe tells the client "No Need to Forward" a bounce. I believe that is the motive of ADSP discard - to reduce backscattering.

Maybe a SMTP extension can do that, call it a NoBounce

  250 NOBOUNCE xyz

where xyz is the optional code used to instruct the client it should not create a DSN for an xyz rejection.

This will assist new augmented 5322 DATA processing technology to create a NoBounce rejection without the need to do a message acceptance.

I like this better than to perpetuate ideas like discarding of mail after message acceptance.

I don't think we can ever get back to the same level of delivery assurance we had before all the abuse, but perhaps we can establish two categories of mail. First class is for senders who offer robust authentication, and maintain an A rating on reputation. Email from these senders can be whitelisted, can expect near 100% reliable delivery, and can be assured of getting a DSN if there is a problem. All the rest can go through the usual spam filters, quarantine, etc.

Since ratings are done by individual receivers (or a group sharing reputation data), the sender cannot assume his A rating will be accepted by all receivers. There must be a way to inform a sender of a "conditional" acceptance. Currently, we have only 250 accept or 550 reject. If you want to send a message, it has to be a reject:

Sorry! We cannot guarantee delivery of this message. - <your domain> does not offer sufficient authentication to prevent
   - <your domain> does not have sufficient reputation for <recipient>.
   We will run it through our spam filter, and keep it in our
   quarantine, but the recipient may not read it.
   See for help.

Perhaps we need a 350 reply code. The command is accepted, but from this point forward, there is no guarantee of delivery. That will certainly motivate any legitimate senders to correct whatever problems they have in authentication.

-- Dave

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