[Orca-users] Spam protection for this mailing list

Blair Zajac blair at orcaware.com
Mon Jul 14 21:04:36 PDT 2003


I'm giving heads up that I've installed the Greylist spam protection
system to all email addresses on orcaware.com.  This will delay the
delivery of your first email to any orcaware.com email address, which
includes any mailing lists and my email address.

This hopefully will save me a ton a time rejecting spam sent to this
mailing list.  So far, I've seen my spam drop from ~200 a day to ~5,
so it's been great.

How does this effect you?  Your email messages will take one to four
hours to go through, so don't except to see it on the mailing list

How does this spam protection work?

The first time you send email to orcaware.com SMTP server,
orcaware.com looks at the triplet composed of the following values:

    1) IP address of the host attempting the delivery
    2) envelope sender address
    3) envelope recipient address

The first time the SMTP server sees a triplet, the SMTP server will
respond to the sending SMTP server with a "temporary failure" message,
indicating that the sending SMTP server should retry in the future.
Normal SMTP servers will retry delivery attempts.  Delivery attempts
made more than 58 minutes and less than 4 hours after the first
attempt are successfully delivered to the recipient.  After the first
email is accepted, all subsequent email that has the same triplet
value will go through immediately.  The triplet's timeout is 36 days.

So even though you don't see your message show up on the mailing list,
it should go through.

How does this block spam?  Most spamming software will make only one
attempt to send an email to a recipient email address.  Because you
and I use normal SMTP servers that perform delivery retries, the email
will eventually go through.

The Greylist software and whitepaper is available at



Blair Zajac <blair at orcaware.com>
Plots of your system's performance - http://www.orcaware.com/orca/

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