[Mailman-Users] Questions about Content Filtering

Stephen J. Turnbull stephen at xemacs.org
Fri Aug 22 19:03:22 CEST 2014

Nancy writes:

 > If :
 > multipart/mixed
 > multipart/alternative
 > were removed would the listkeepers, as owners of the group receive
 > bounces from everyone who tried to send formatted text?

Whether the owners would receive notification depends on the
filter_action (last option on that screen), which can be Discard
(silently), Reject (and return to sender), Forward to List Owner, or
Preserve (save in a special place for later use by list owners).  Only
in the "Forward" case will you get a notification.

As for "formatted text", that depends on what else is in
pass_mime_types.  If only text/plain is there, there is no way for
HTML formatting to get in.  However, it won't stop any of the problems
you list below from occurring.

 > If these two lines were changed from "Yes" to "No" what would happen?
 > Should Mailman collapse multipart/alternative to its first part
 > content?  No Yes
 > Should Mailman convert text/html parts to plain text? This
 > conversion happens after MIME attachments have been stripped. No
 > Yes

If you remove the multipart lines from pass_mime_types, these two
lines have no effect.

If you keep them, the effect depends on the sender, but normally the
message will be converted to plain text.  However, plain text may
include "unusual" characters like those in your samples below.

I think you should try the following:

1.  add text/html to pass_mime_types.  Ie, it should read


2.  set collapse/alternatives and convert_html_to_plaintext to no.

Of course this means that HTML formatted messages will pass through,
but I wouldn't be surprised if the "mail programs for the rest of us"
handle HTML better than they do plain text.

BTW, I don't think this specifically has anything to do with tablets
or cellphones.  Similar problems occur with email programs for PCs.

 > Examples of our current problem:

As far as I can tell your examples were corrupted in transmission (and
then corrupted again when Robert quoted it -- it appears differently
in his message.

For us to learn more about the problem, we need to see the problem
messages, including all header and formatting material, preferably in
two versions, both as received by the Mailman server, and as resent to
list members by Mailman.  Since message content is the problem, they
should be verbatim, no editing at all, just resend the whole thing.

That's up to you, of course, and you should consider the privacy of
your members.  If you can get those copies, and you feel the content
is sufficiently un-sensitive that the users wouldn't mind (or better,
you can get permission) feel free to send them directly to me
<stephen at xemacs.org> and Mark Sapiro <mark at msapiro.net> (this list is
archived and available to the public, so your users' addresses and
names would be Googleable -- best to avoid that). 


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