[Mailman-Users] Settings for filtering messages with attachments

[Paul Kleeberg]

Forgive me for asking what may be obvious.

I am about to restart a list that was on listproc.  I want to use 
content filtering but I am not clear what it does to the archives, to 
the messages or to the digests.  I have read the documentation on the 
Content Filtering page and sent several types of messages but I am 
still confused.

Initially I had it set to "No".  I sent a message in rich text and it 
appears to go through unfiltered but the archive has a message that 
is text only with a URL pointer to an attachment.bin that I cannot 
seem to open.

 From the documentation:
>Content filtering works like this: when a message is received by the 
>list and you have enabled content filtering, the individual 
>attachments are first compared to the filter types.  If the 
>attachment type matches an entry in the filter types, it is 
>discarded.

Does "IT is discarded" refer to just the attachment or the whole 
message?  I assume the attachment.

>Then, if there are pass types defined, any attachment type that does 
>not match a pass type is also discarded.  If there are no pass types 
>defined, this check is skipped.

So the default is to allow multipart/mixed, multipart/alternative, 
and text/plain to pass through.  (I am really not clear what these 
may house except for plain text.)  So these are the only sections 
that are allowed to pass (if filtering is enabled otherwise 
everything gets through)  What about text/html?  Does that get 
through?

>After this initial filtering, any multipart attachments that are 
>empty are removed.  If the outer message is left empty after this 
>filtering, then the whole message is discarded.  Then, each 
>multipart/alternative section will be replaced by just the first 
>alternative that is non-empty after filtering.

I take this to mean it the message has only rejected sections and all 
that is left is the shell of the message, then the shell is 
discarded, otherwise the first section that makes it through becomes 
the the first section in the message

>Finally, any text/html parts that are left in the message may be 
>converted to text/plain if convert_html_to_plaintext is enabled and 
>the site is configured to allow these conversions.

How does text/html get through to this point if it is not in the 
pass_mime_types?  If I want text/html to be converted, do I have to 
put "text/html" in the pass_mime_types?

But does this have any effect on the archives?  (It seems it I turn 
on filtering that there is no "attachment.bin")

What does it do to the appearance of the digests?

I guess ideally I would all mail to go out as text and any 
attachments stripped and potentially stored with a url for retrieval 
by the willing.  Am I dreaming?

I guess I need a tutorial on the anatomy of a multipart message. 
Anyone know where I can find one?

Paul
(just enough knowledge to be a hazard to myself)
-- 
Paul Kleeberg
paul at fpen.org