[Mailman-Users] Need help with "content filtering"

Mark Sapiro msapiro at value.net
Sat Mar 5 18:46:23 CET 2005

Pete Holsberg wrote:
>I decided to create a test mailing list to experiment with 
>content filtering. Incidentally, this is Mailman v2.1.5.
>Edit filter content: YES
>Filter mime types: (blank)
>Pass mime types:
>	multipart/mixed
>	multipart/alternative
>	text/plain
>	text/html
>Convert HTML to plaintext: (see below)
>Filter action: Forward to list owner
>I created a simple two-line HTML "page" in Word and pasted 
>it in to Outlook (set to send HTML) but without stationery.
>It didn't matter whether "Convert HTML to plain text" was 
>YES or NO: In both cases, all HTML font formatting was 
>stripped out. However the link I had in the original was 

I think what's going on here is the original message is
multipart/alternative with both a text/plain part and a text/html
part. If more than one sub-part remains in a multipart/alternative
part after filtering, Mailman selects the first remaining alternative
which would be the text/plain part in this case.

There are two ways to get the HTML part to the list in this case. One
is to not allow text/plain at all. This is probably a very bad idea
for a discussion list, but might be viable for an announcement list
where the intent is to always post HTML. The other is to set up your
MUA (Outlook) to send HTML only, not multipart/alternative.

>I'd be happy to email the simple test page to anyone off list.
>This is really confusing me!
>If my HTML page has an image in it ("stationery"), it will 
>be treated as an attachment. Won't Mailman remove it because 
>it doesn't have an approved content type? It doesn't. 
>Instead it blocks the message and sends me this:
>"The attached message matched the XXX mailing
>list's content filtering rules and was prevented from being 
>on to the list membership.  You are receiving the only 
>remaining copy
>of the discarded message."
>When I send the same page without the image, the message is 

What this means is content filtering removed the entire message. This
may be a problem with content filtering or it may be the way Outlook
structures this message. I can't say without seeing such a message as
received by Mailman. If you want to Cc: me directly with one of these
test posts, I'll look at it and tell you what I think.

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

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