nanog mailing list archives

Re: Blocking mail from bad places


From: John Levine <johnl () iecc com>
Date: 4 Apr 2007 19:43:24 -0000


While its a pretty brute force approach, one method I’m trying is to
curtail the source of email. In otherwords, if smtp traffic comes from an
unknown source it gets directed to a sendmail server that intentionally
rejects the email message (550 with a informational message/url).

1) You send bounces from spammers to innocent people, whose
addresses have been forged.

This is an SMTP reject, not a bounce.  It's a lethal variety of
greylisting.

This technique works great to keep spam out of your mailbox.

3) You are dropping valid emails.

Right.  It also quite an effective way to be sure you never hear from
non-technical users who don't understand your bounce message, and from
people like me who don't feel like jumping through your hoops,
particularly in a case like this where we're responding to a question
you asked.

R's,
John


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