[Mailman-Users] Digests and HTML-enhanced email

Mark Sapiro mark at msapiro.net
Sat Oct 22 16:03:33 CEST 2011

Lindsay Haisley wrote:
>> Message: 25
>> Date: Fri, 7 Oct 2011 08:42:29 -0700
>> From: "foo bar" <.......>
>> To: Cyberpluckers at autoharp.org
>> Subject: Re: [CP] Intro
>> Message-ID: <a0ffed34-525e-40a5-88c6-4b78dbef2df8 at blur>
>> Content-Type: text/plain; charset="us-ascii"
>> An HTML attachment was scrubbed...
>> URL:
>> http://www.autoharp.org/mailman/blah/blah/..../attachment.html
>> ... <snip> ... other examples
>I took a look at the list archive and indeed the email appears in the
>archives also with only a link to the attachment, which is the
>HTML-enhanced message, visible as HTML code.  There's no plain text
>version in the archive.

Stephen and Brad have already replied, and I'm not going to repeat what
they said. I'm only going to reply to a few specific technical issues.

The above message excerpt is from a plain format digest. This CAN be
avoided in the digest by subscribing to the MIME digest, but it cannot
be avoided in the archive. All non-plain text parts of a message will
generally be scrubbed for the archive. There is some control over how
scrubbed HTML is rendered in the archive. See the documentation for

>I explained to the subscriber, and to the list admins, that this (and
>similar) posts were probably HTML-only posts, and that, absent a plain
>text rendering in a multipart email, the list server had no way to
>generate a plain text version, and that including multiple HTML-enhanced
>emails in a digest was problematic and not going to work very well, if
>at all.  The list admins are aware that plain text is the appropriate
>format for posting to a mailing list, but subscribers come and go from
>this list, and as I said, many don't understand such things, and it
>seems that there are a number of mail programs out there which will
>generate an HTML-enhanced email without an accompanying MIME text/plain

Content filtering can convert HTML to plain text using lynx, elinks or
a similar program.

>The list is configured with mime_is_default_digest set to MIME, which I
>assume sends digests with each post as a separate attachment (I've never
>subscribed to the digest for this list, so I don't really know).  I had
>assumed that this might address this problem, but apparently not.

It only sets the default for new subscribers. The subscriber above is
receiving plain digests.

>One of two things needs to happen.  Either the list server should refuse
>and bounce posts with no MIME text/plain part, or some more intelligent
>configuration of Mailman needs to be available so that posts within a
>digest will render properly under these circumstances.  Maybe a more
>recent version of Mailman can do this, I don't know.  Any suggestions
>would be appreciated.

Content filtering can remove HTML or convert it to plain text and
Discard, Reject (problematic as Stephen notes) or Forward to Owner
posts which are empty after filtering.

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

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