[Mimedefang] Off Topic: Refuse Null Sender

[Jim McCullars]

On Tue, 3 Jul 2007, Jason Bertoch wrote:

> relay mail from the null sender.  Blocking this will seem to eliminate some
> back-scatter as well as botnet spam.  I've tried various methods with the access
> table to no avail.  Any ideas?

   You can easily do it in MIMEDefang:

sub filter_sender {
   my ($sender, $ip, $hostname, $helo) = @_;
   if ($sender eq "<>") {
     return ('REJECT', "Null envelope sender not allowed")
   }
   return ('CONTINUE', "ok");
}


   HTH...

Jim McCullars
University of Alabama in Huntsville