[Mailman-Users] Digests and HTML-enhanced email

[Brad Knowles]

On Oct 21, 2011, at 11:21 PM, Lindsay Haisley wrote:

> 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's not done as a separate attachment, it's done as separate MIME bodyparts, which some MUAs might render as "an attachment" -- particularly, the more brain-dead ones.

> 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.

Mailman can flatten HTML to plain text on ingest, and when the MIME format digest is generated, that should look mostly kinda semi-sorta correct -- at least, on the majority of less brain-dead MUAs.  For MUAs that don't generate text that can be flattened, that should result in what would appear to Mailman to be an "empty" message, which should be silently dropped.  Some users might wonder what is happening to their messages, if they're submitting with a really brain-dead MUA.

Of course, there is still the issue of what to do with any real attachments that might have been included.  Mailman can silently strip those, or it can scrub them and put them in the archives, replacing the actual attachment content with a link to the scrubbed attachment in the archives.

All of this can be done on the version of Mailman that you have today, but more recent versions of Mailman might have other advantages that you might also appreciate.

> I rather dislike HTML-enhanced email (to put it gently).  There's no
> fixed standard for it, and what renders one way in one mail reader
> renders some other way in another mail reader, and it confuses the hell
> out of list servers.  But people will use it, increasingly it seems, and
> insist on doing so, so somehow this kind of problem needs to be dealt
> with.

I think that the tools are already there for the bulk of list admins to deal with the bulk of problems.

The only outstanding major issue that I know of that we can't fix right now is the handling of appending footers to MIME-formatted messages which can be rendered by some brain-dead MUAs as separate "attachments".  So far, the consensus has been that we won't kowtow to those brain-dead MUAs, and if the users in question can't deal with these separate "attachments", then the list admins are going to have to forgo putting footers on messages as they are being passed through the system.

--
Brad Knowles <brad at shub-internet.org>
LinkedIn Profile: <http://tinyurl.com/y8kpxu>