Can the null address be specified in a ruleset?

[Jim Holland]

Hi Julian

I have a user who is receiving numerous erroneous bounces of "cleaned"  
viruses from a large local ISP.  The viruses are spoofing her address.  
The envelope sender address according to the log file is the null address
<>, although when received by the user it has the envelope address
MAILER-DAEMON at mango.zw that is added by our own system (mango.zw) after
receipt.  I have tried the following in spam.blacklist.rules:

	From:   <> and To: user at mango.zw          yes
and
	From:   MAILER-DAEMON at mango.zw and To: user at mango.zw          yes

but, not surprisingly, neither of these work.  Can you suggest any way to 
make such a rule work?  Or would it need to be a new feature?  I do think 
it would be very useful to be able to use <> if it cannot be done at the 
moment.

I am not using SpamAssassin (don't have enough horsepower) so cannot use 
that.  And I don't want to block other mail from the major local ISP that 
is sending this junk.

For the moment I will just try getting them on the phone once more . . .

Regards

Jim Holland
System Administrator
MANGO - Zimbabwe's non-profit e-mail service