On Wed, 30 Aug 2006, Frank Ellermann wrote:
SPF NONE, no PTR, invalid HELO, no guessed pass (3 strikes)
Is that "invalid HELO" defined as "NXDOMAIN" ? You could also
reject this. Maybe RFC 2821 mumbles something about "only for
logging", but you're free to reject any mail if you don't fear
RFCI listings.
I *could* reject these, and I do for my own domain. But my clients
can't afford to miss mail from potential customers with braindead
email setups. Spamcop is effectively pressuring me and my clients to just blow
off these people that can't configure their email (and can't use
a competent 3rd party for email - not every smart person is a computer geek).
But my clients don't see it that way.
There need to be friendly ways for non-computer geeks to evaluate
3rd party email providers. I have found dnsreport.com to be useful
in that regard. They might not understand the things being checked,
but RED = "bad" and YELLOW = "maybe bad" can help their evaluation.
And dnsreport.com is pretty good with their flags.
ACK. But I've read somewhere that 84% of all mails are spam,
11% misdirected bounces, only 5% are legit. If you care too
much about the 5% you contribute to the 11% making it worse
for innocent bystanders.
I send 1 DSN per braindead mailbox per month. The rate is very low.
Just publishing an SPF record, even a default neutral one, prevents the DSN
(but bad domain reputation may lead to reject on neutral).
clients are concerned about missing email from email-clueless
customers.
Tricky. Maybe add some decent BLs to the reject-logic, if you
want to send DSNs you can take aggressive BLs - a recipe as for
an outsourced backup MX while the primary MX is down.
Already have that. But spammers are constantly churning through
throwaway domains.
Eventually those clueless senders need to get a clue.
It's your decision, you can accept NONE like PASS and follow
the obsolete 2821-rules, or you can treat it like FAIL for any
plausible reason. Clueless senders should understand a reject
if you state this plausible reason in the 5xx response. Maybe
add an URL of the boilerplate explanation instead of putting
it into a DSN.
Yes, I will be working on webpages to reference in SMTP REJECTs.
I am skeptical that these clueless senders will be able to cut and paste
the link, but it is worth a try.
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flammis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.
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