The short version is that each message in a chat appears as a different conversation to regular mail users on some popular webmail systems. To be clear, this issue applies to one-to-one chats, not group chats (which has been been well-resolved in my view).
The long version is that by experimentation, I believe that at least GMail and Outlook webmail group conversations based on In-Reply-To and subject matching. So a correctly threaded reply will appear to be a different conversation to a GMail user if the subject has changed. DC changes the subject for each message in a one-to-one chat, but even though it handles the other headers absolutely correctly, a long thread will end up looking like quite a mess to users of many popular āMUAsā.
The behaviour of GMail/Outlook/etc. is very odd from my PoV as a āmuttā and āK9ā user. Some might even say ābrokenā, but I think this is a practicality vs. principle issue - DC has to be able to communicate smoothly with ānormiesā, thatās itās unique selling point.
That said, Iām not quite sure what the answer is.
Customisable subject maybe? Makes DC less like a chat-app
Stick with a single subject thatās somehow inferred? Is it the first message in the chat? In which case, itāll need to be changeable at some point, or conversations with your best friend will bear the subject āre: Hey, I found this cool new chat appā 5 years later! Perhaps some heuristics to decide when a āconversationā is over based on time gaps, and itās ok to then reset the subject?
I very nearly added this to the āSubject of emailsā thread, but that went so far into being group-specific that I worried about being off-topic. FWIW, I quite like the solution to group chat, as that resolves this GMail/Outlook problem very nicely.
My primary motivation is that Iād like to spread DC among many more of my colleagues, but this subject issue appeared to be the show stopper (out of several smaller issues).
Even for the first colleague who agreed to use it on daily basis as main textual communication channel with me (this is also the most technically oriented colleague of those tens waiting).
Basically there are two issues:
threading in Gmail doesnāt work (my colleague told me it quickly made a huge mess in his gmail)
subject is being changed by non-DC activity (causes severe confusions and significantly contributes to the overall mess)
Both issues stem from the fact, that my colleague (and me too) wants to use an email account for 2 different things:
emailing as usually (including frequent forwarding of some formatted emails with PDF attachments to my email account which I use in DC in addition to an ordinary email client)
chatting as an additional use case of the account
Of course, the easiest solution would be to use a fixed unchangeable subject for any message sent by DC in a 1-on-1 chat. This shall easily solve both issues above. I didnāt put much thought in it, so it might have also some serious flaws.
At least as temporary solution to not discourage users, it seems viable to me.
The flaw is that we have to decide on one subject for everyone and Re: <previous subject> is maybe the subject that normal email users use the most (just reply to the last email).
BTW you can reply to another message by swiping right on this message, this will also change the subject.
Other idea: Maybe now, with all these email-compat things being done, (or, in some months when all these some of the ongoing projects are settled) is the time to make the subject user-changeable?
I think on Android we can put this into the overflow menu and remove View profile, Add attachment and Archive chat because all of these can be accessed in other ways and I donāt think I personally ever used them.
if the sender set a custom subject using DC, we should probably also show it for the receiver using DC. Maybe just introduce another custom header Chat-Show-Subject.
and