[Greylist-users] Possible Enhancements

[James J Dempsey]

> What if the greylisting process checked for an MX record, and did a 
> simple callback to see if the server was live?  If the answer is yes to 
> both, then allow the mail through.

There are lots of spam where the from: field lists a valid user on a valid
host with a valid MX record.  It just happens to be someone whose name has
been hijacked for this purpose, not the actual spammer.  This is often
called a Joe-job.

In this case, or in cases where the spammer simply uses "From:
fill-in-the-blank at yahoo.com", this technique would completely  eliminate the
effectiveness of greylisting.  Unless I'm not understanding your proposal properly.

                       --Jim Dempsey--
                         jjd at jjd.com
                       http://jjd.com/