Enhancement: support for more content types

[dumblob]

Nowadays it's quite common to send e.g. calendar invitations by email. Such email may have many Content-Type: headers. E.g. Google Calendar sends:

Content-Type: multipart/mixed
Content-Type: multipart/alternative
Content-Type: text/plain
Content-Type: text/html
Content-Type: text/calendar
Content-Type: application/ics

The ics part has Disposition: attachment, but all others are "inline". It would be very nice to have separate viewers (e.g. as Cypth modules) for different types - I can think of 3 basic ones (text/plain, text/html, text/calendar) and one more as my little personal wish (text/x-markdown and text/markdown). These viewer might be configurable (e.g. it's insecure to download all embedded/linked images when viewing the text/html content, so in configuration there would be a choice "show immediately" or "show a button load images" instead by default).

The goal would be to allow switching between them on demand. In a long run, some semantics can be used - e.g. the text/calendar viewer might render it using schema.org under the hood or provide direct links accept deny tentative in case you have a Gmail account.

[dumblob]

Now I noticed, that

Content-Type: message/rfc822

(sometimes incorrectly called eml) is being used (not sure how frequently) for forwarding messages etc., so it's another low-priority candidate for a separate viewer ;)

[jasonmunro]

Currently, formatting for different MIME types is contained in the IMAP module set, with a few bits in the "core" set (so other module sets, like POP3/feeds, can leverage them). I'm intrigued by the idea of abstracting these to individual module sets, but not sure yet if that is a good idea. Maybe MIME type formatting should be in the core set, or maybe a dedicated module set just for formatting different types. Great food for thought either way, so thanks yet again!

[mat-m]

I put a +1 on this.
Windows Live Mail sends Content-Type: multipart/alternative

with the text part beginning with

------=_NextPart_000_0080_01D1797B.99F0ABC0
Content-Type: text/plain;
    charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

The text part is not displayed in the inline message, and we don't have the download links for the many parts. Could you confirm it is related to this issue or if I should open a new one ?

[jasonmunro]

Multipart alternative messages are supported, it is a common message "container" type when sending a a message with plain text + html markup. If you have one that is not displaying properly, that is a different issue or potentially a bug. If you could open a new issue for that I would appreciate it!

[jasonmunro]

As a part of general issue cleanup, and an attempt to remove "generic" issues that are hard to actually address, I'm going to close this. Cypht supports a message parts section for IMAP messages that correctly shows all message part types and structure (IMHO, more so than any other webmail or desktop client I know of). What we lack is specific support for doing something with some message part types. For each of these we would like to support, I would like to create a specific issue so it can more directly be addressed.

Of the original types listed in the OP, the only types Cypht does not know how to do anything with (except provide a download) is the ics/calendar types. This is already covered in another issue (maybe 2), and s a part off some new work on CalDav/CardDav support that will hopefully be changing soon!