Can the null address be specified in a ruleset?

[Matt Hampton]

Jim Holland wrote:

> 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.

If you are using sendmail and are willing to use milters then checkout
milter-regex.  I use this for exactly the purpose you have described.

http://www.benzedrine.cx/milter-regex.html

matt