[Mimedefang] Off Topic: Refuse Null Sender

[John Rudd]

I would like to point out that while this works, it's a bad idea.

It's an RFC violation to not accept mail from null senders.

Better to accept it and throw it away (probably still a violation of the 
spirit of the RFC, but no on will know you're doing it, and thus wont 
report you to the RFC-Ignorant blacklists).

Best yet: accept them and deliver them.  Let the user figure out how to 
handle it.


Jim McCullars wrote:
> 
> 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
> 
> 
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