On Mar 11, 2007, at 2:55 PM, John L wrote:
I phrased it wrong. You are not responsible for the content, but
you are responsible for the mail domain and that includes
verifying that mail is validly from your domain you are
Oh, OK. So if someone sends pump and dump with a [EMAIL PROTECTED]
return address, and I do a callback and your MTA says "yup! that's
a 100% valid address!" then I turn you in to the SEC, rignt?
You do know what the SEC is, right?
You have now confirmed that the mail is from you, after all.
No, it only confirms that the sender address is an actual address.
Or if you haven't, what purpose did the callback serve?
It served to identify that it is possible a valid email. A failure
is almost definitely a non valid email. It is a test which helps
determine whether to accept it. We have a policy of not accepting
mail from people who cannot accept DSNs back. That does not mean we
give a blanket pass to those who pass address verification.
There is some reasonable validation technology coming along, most
notably DKIM which which I presume you are familiar. But callbacks
are not it.
Callbacks are one tool in the toolbox. Maybe someday there will be
better tools and we can retire address verification. Callbacks, at
this point in time, work very well for differentiating a large amount
of non valid mail from a smaller pool of possibly valid mail.
DKIM is interesting and I am watching it. I am in the process of
adding some support for it btw, both for our authorized senders, as
well as in our receive phase. For example, we are considering not
doing address verification on incoming mail that has a valid DKIM
and you are breaking the RFCs. (valid verification includes
checking that the sender can accept a proper DSN back, which is
required of the sender to do).
Uh huh. Which RFC is this that says I have to permit a fake
partial DSN transaction? If you have a DSN, send it. If you
The RFCs require you to accept back DSNs. Testing that you do is a
valid test to see if I am talking with a valid sender -- one who
implements the RFCs and is not a rogue internet user who does not
cooperate in the exchange of emails according to the agreed standards.
Show me some real verifiable numbers that show that verification
traffic to your box is a significant portion of the otherwise bad
traffic of mail bombs, bounces, etc. On my system, and we support a
lot of mail domains, some of which (now or in recent past) we "big
name" domains that had a lot of exposure. Address verification
traffic has always been small compared to our overall load.
You are complaining about a non issue. I can say that address
verification helps us reject the lion's share of spam we receive
without having to process it further.
Don't forget that the From: line address need not be the same as
the bounce address; in my mail it never is.
Chad Leigh -- Shire.Net LLC
Your Web App and Email hosting provider
chad at shire.net
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