[Exim] filtering ideas for stopping spam: Message-Id

Sometimes I receive spam with no Message-Id or it is set to <>.

Does anyone have any advice on whether I should block mail with
missing Message-Id or set to "<>"? (Does anyone have success with this?)

From reading rc822, I can't tell if a missing Message-Id is invalid. It
does indicate that it is a standard. It does look like "<>" is invalid
though because it is missing the 'local-part "@" domain'. (I guess I
should also look at updated rfc's.)

I also have some local systems that send mail to the mail server without
Message-Id's. (Plus when testing, I usually don't include a Message-Id,
because I let the server add it.) Does anyone have any examples on
blocking some mail without Message-Id's?

Also, I am looking for more filtering ideas. Does anyone have any links to
collections of exim filters?

(Or would anyone be interested in creating or contributing to make a
collection of exim filters?)

Thanks,

  Jeremy C. Reed
                              FAQs for ISPs
                              http://www.isp-faq.com/