[Mimedefang] Blocking Missing Message-ID

[Joseph Brennan]

--On Thursday, April 12, 2007 18:25 +0800 imacat 
<imacat at mail.imacat.idv.tw> wrote:

> Dear all,
>
>     Hi.  I notice over 2/5 of my "remaining" spams are missing a
> Message-ID, which is then added automatically by my sendmail MTA
> afterwards.
>
>     I'm thinking about blocking all the messages without a Message-ID,
> that comes from unauthenticated clients in foreign networks?  Is this
> dangerous?  Is it possible to block legal mails for this?


Message-ID is not a required field.  Some software used by legitimate
organizations to send announcements and newsletters sends without a
Message-ID.  You'd miss some professional and hobby communications
if you reject for it being missing.

It's worth scoring for it being missing.  See Spamassassin's rule for
MSGID_FROM_MTA_ID.

Joseph Brennan
Lead Email Systems Engineer
Columbia University Information Technology