Blocking mail from bad places

Wed Apr 4 19:43:24 UTC 2007

>> While its a pretty brute force approach, one method Iâ€™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