Delta-core to always refer to last message for improved non-Delta mail app threading

[hpk42]

When i write a mail with my non-Delta mail app to Delta/Android and Delta/Android replies, it shows up in a totally different mail thread, i.e. does not reference my mail. I suggest that Delta always references the last mail in a message chat window -- seen from the non-Delta mail app that feels natural and for Delta/Android it doesn't change anything: the message and its replies will simply appear in chronological order.

[r10s]

Would it help if Delta Chat uses the same References header as the mail from the non-Delta-Client?
In fact, Delta Chat generates a random one to keep things for other MUAs together (see here) - obviously, this does not work for the first reply.

Using the In-Reply-To: does not work well - many MUAs are not prepared for threads nested very deeply which would happen with Delta Chat very easiy, see deltachat/deltachat-android#36 (comment)

[valeriopaladino]

Maybe this could be made into a configurable option? Apparently the In-Reply-To header could use the same logic used for Chat-Predecessor (

deltachat-core/src/dc_mimefactory.c

Line 562 in 0d122fc

mailimf_fields_add(imf_fields, mailimf_field_new_custom(strdup("Chat-Predecessor"), strdup(factory->predecessor)));

), or maybe use the first message in the tread, to have a single flat thread in Gmail (which is how the mails are displayed in Evolution right now).

[hpk42]

It's worth a try IMO to set "in-reply-to" to the first message in a chat, instead of the last one. It would avoid threading. @r10s or was there something that makes this a bad idea?

[r10s]

@hpk42 we can try just try it and see how this works.

might cause some problems if the original message is very old and maybe deleted or so. not sure.

[r10s]

@hpk42 the commit ec9418a references the newest message not sent by SELF. this was simpler and more straight forward and seems to cause less problems for a first shot.

if there is no newest message not sent by SELF, currently no threading happens (we can fix this, however, maybe fix the "larger" questions first :)

always using the oldest one would be just a change from min() to max() in the select statement from the linked commit, however, as mentioned, if this is sufficient, it will be easy - if we want a new anchor every some days or so, it would get more complicated.

EDIT: what may cause problems when referring to the first message are top-level messages sent from other MUAs - answers to these mails would be sorted to a different thread then.

let me know what you're thinking :)

[testbird]

Would it help if Delta Chat uses the same References header as the mail from the non-Delta-Client?

That!
Exept for MUAs not supporting the References header, it would likely be the better (default) solution. Not depending on a continuous history, and no deep nesting of messages.

The full threading may still serve as a very good per chat option!

[testbird]

If there is no explicit References header in the received non-Chat message, the References in the reply may be set to the message ID of the received non-Chat message (instead of a randomly created one).

[ghost]

Why is this issue closed? It still exists. MUA users still receive seperate emails from me clogging up their inbox.