On 1/18/19 5:11 AM, Henrik Rasmussen wrote:

Please correct me if I'm wrong, but as I understand, Mailman attaches posts in a MIME Digest mail intead of inline in the digest mail itself, like Plain Text Digests does. Some mail readers like Gmail eventually displays attachments inline anyway, but readers like Outlook do not. Also the digest index seems to be posted as an attachment in MIME Digests.

Would it be possible for Mailman to send both posts and index inline in the MIME digest?

The format of the MIME digest is specified by RFC 2046 which defines the multipart/digest format in section 5.1.5. This defines the MIME digest as a multipart/digest message part containing the individual messages as message/rfc822 sub-parts. It also says (after spelling corrections - ErrataID: 510):

Note: Though it is possible to specify a Content-Type value for a body part in a digest which is other than "message/rfc822", such as a "text/plain" part containing a description of the material in the digest, actually doing so is undesirable. The "multipart/digest" Content-Type is intended to be used to send collections of messages. If a "text/plain" part is needed, it should be included as a separate part of a "multipart/mixed" message.

The MIME format digest Mailman produces has the structure

multipart/mixed text/plain the "masthead" text/plain (only if a digest header) the digest header text/plain the table of contents multipart/digest message/rfc822 the first message message/rfc822 the next message ... message/rfc822 the last message text/plain (only if a digest footer) the digest footer

The only change that could be made while keeping the digest compliant would be to combine the masthead, digest header if any and table of contents in a single text/plain part.

While this might solve the the issue of the table of contents being an "attachment" in some MUA's rendering, it won't address the larger issue of the messages being rendered as attachments.

As you note, Gmail's web mail does an OK job of rendering the MIME digest as do other mainstream MUAs such as Thunderbird. The real solution is for those people who insist on using non-compliant MUAs to subscribe to the plain format digest.

The whole point here is if you want a digest which has everything in line, that's what the plain text digest is. If you want a digest which maintains the original structure of the messages without flattening them to plain text, the messages have to be separate message/rfc822 parts.

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