[Info-vax] inhibit email with From: <> from being sent

[Bob Eager]

On Fri, 30 Dec 2011 22:23:23 +0000, Phillip Helbig---undress to reply
wrote:

> In article <9m3ce5F3gnU2 at mid.individual.net>, Bob Eager
> <news0001 at eager.cx> writes:
> 
>> > In the log of my SMTP relay server, I occasionally see a record of
>> > emails sent from the adress "<>", i.e. with an empty From: header.  I
>> > suspect this is some sort of backscatter spam.  (In general, a
>> > combination of RBL and setting Symbiont-Checks-Deliverability: to
>> > FALSE has stopped most of my spam.)  Is there any way to prevent this
>> > from being sent?
>> 
>> No, it's a valid thing to do. Read RFC 5321, section 4.5.5 in
>> particular.
>> 
>> It is not backscatter spam - in fact, it's almost the opposite.
> 
> I had a quick glance: delivery-status notification or something like
> that.  But the address is not one I recognize (I have NEVER noticed such
> an email getting sent to an address I recognize), so I am assuming that
> while perhaps it SHOULD be generated, maybe someone sent a spam email to
> a non-existent user (with more than 12 characters, so that my old
> version of SMTP doesn't just drop it) and this is the automatic response
> to that.  But suppose the From: address is bogus; in that case it would
> be backscatter spam, right?

Could indeed be. The answer there is to reject it via the From: address 
rather than the <>, which would be dangerous.



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