Method to drop unknown user messages to black hole

[Anthony Tibbs]

Hi Bob,

Perhaps I am missing something here, but with my Postfix setup (which is based on two instances of Postfix + amavisd-new + Cyrus), messages are checked against a user database at the outer postfix, and rejected during the SMTP connection for invalid recipients, before lmtp/etc. even sees it.  For me, this requires that user logins/authentication be handled through a MySQL database, but is this an option for you?  

It avoids almost all of the backscatter issues... though may not be the best setup for everyone.

Take care,
Anthony

  ----- Original Message ----- 
  From: Bob Bob 
  To: Cyrus Maillist 
  Sent: Friday, July 13, 2007 10:52 PM
  Subject: Method to drop unknown user messages to black hole


  Postfix & Cyrus

  Have been finishing off the server ready for accepting external smtp
  connections. No more fetchmail...

  I note that in todays spam environment more and more administrators are
  choosing to black hole any messages with invalid recipients. In a
  standard postfix setup this is pretty easy with luser_relay. When
  however you use lmtp, local delivery really only looks at /etc/aliases
  until it passes through to cyrus.

  My first question is a general one. Do you all choose to send
  reject/nonexistent user messages or just black hole them? Rejecting is
  obviously the simplest solution but I am concerned about being
  blacklisted from sending garbage back out. There are ways of course to
  stop backscatter happening but I am also concerned that there are valid
  bounces being created that the (real) sender needs to know about. I'd
  like to hear what your solutions have been.

  My second question is how to you accomplish a black hole with cyrus? I
  had thought that a "global" sieve script would do it but note that this
  is user specific. I see nothing specific in lmtp that points to that either.

  I note this has been discussed previously but I didn't find an actual
  resolution beyond allowing auto mailbox creation!

  Thoughts appreciated

  Bob
  ----
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