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Re: Help with filtering the sender

2006-10-02 17:39:32
At 16:24 2006-10-02 -0600, Google Kreme wrote:
Setup your mailserver to ONLY accept mail for real and valid
accounts.  You can do most of this in /etc/postfix/virtual (or
whatever) like this:

amazon(_at_)mydomain(_dot_)tld  myemail+amazon(_at_)mydomain(_dot_)tld
procmail(_at_)mydomain(_dot_)tld myemail+procmail(_at_)mydomain(_dot_)tld
etc.

Of course, just using plussing right off helps shed spam and 
viruses.  Seems a fair number of address harvesters don't grok + as a 
legitimate email address component, and so they parse the RHS of the 
plussed address (when moving outwards from the @ symbol they often anchor on):

myemail+procmail(_at_)mydomain(_dot_)tld

is very likely to be harvested as procmail(_at_)mydomain(_dot_)tld(_dot_)  If 
you don't HAVE 
a procmail(_at_)mydomain(_dot_)tld (and don't foolishly use wildcarding), then 
mail 
sent to the improperly parsed address will fail to deliver.

I don't have control at SMTP level, only what procmail can do for me.

Then move your domain to a better ISP.  If you can't reject mail for
unknown accounts then you're going ot be totally, completely, and
most importantly, repeatedly fucked.

Heck, it's in the ISP's best interests to reduce the flow of spam through 
their servers, since it's wasted bandwidth, processor power, and disk 
space.  Of course, there are those who figure if you have a disk space 
quota, if it happens to fill up and you go to an overlimit charge, that's 
beneficial to their bottom line...

What you need to do for now is a positive match.  Create a file with
all your valid email addresses and then match against that.  If it
doesn't match, drop the email.  That means matching on the To: field.

Or X-Envelope-To, or somesuch, if one's mailhost sets it.

---
  Sean B. Straw / Professional Software Engineering

  Procmail disclaimer: <http://www.professional.org/procmail/disclaimer.html>
  Please DO NOT carbon me on list replies.  I'll get my copy from the list.


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