[Mailman-Users] Postings being discarded due to DKIM failures?

[Mark Sapiro]

On 05/15/2014 08:43 AM, Robert Heller wrote:
> A list member recently tried to post a message to a list and the message was 
> discarded for no *appearent* reason.  The only clue is that for some reason 
> the message is failing the DKIM check (DKIM=fail).  I am using Mailman 2.1.16 
> on CentOS 5 (python-2.4.3-56.el5, httpd-2.2.3-85.el5.centos, 
> dkim-milter-2.8.3-8.el5).  Is there some way to get Mailman to log why it is 
> discarding messages?


I assume you've seen the vette log entry saying the message was
discarded, but it doesn't say why.

Essentially all discards are because the message met some condition for
which the action is Discard. These are all in the list's web admin
interface. The most common one is Content filtering with a filter_action
of discard and a message whose top level Content-Type: is either in
filter_mime_types or not in pass_mime_types. This could be, e.g., a
multipart/related message with multipart/alternative and multipart/mixed
as the only multipart types in pass_mime_types or a text/html message
without text/html in pass_mime_types. It is a common misconception that
convert_html_to_plaintext will handle the latter, but you have to accept
the HTML before you can convert it.

Other places to look for Discard actions are:

Privacy options...
    Sender filters
        member_moderation_action
        dmarc_moderation_action (Mailman 2.1.18 and up)
        discard_these_nonmembers
        generic_nonmember_action
    Spam filters
        header_filter_rules

If you want to see the reason and the message, change the action from
Discard to Hold.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan