Support normal mails in DCC for hybrid clients

Feature Proposal
1

As a pre-requisite for Make DC a replacement for MUAs? and hybrid chat/mail clients in general, the DeltaChat Core library should support sending and receiving arbitrary MIME mails.

I see several ways to add the API to DCC, in order from least to most abstraction:

  1. Send/receive raw bytes. Not stored in DCC database.
    Folders are simply strings representing the full path, i.e. starting with “INBOX/”.
    • pro: least effort for DCC
    • con: most effort for DCC clients, duplicate DCC functionality
    • con: need to expose more internals to access e2ee keys, etc.
  2. New class allowing direct access to libetpan. Optionally stored in DCC database.
    Folders have their own class.
    • pro: reduced effort to implement now
    • con: more effort for clients on migration away from libetpan
  3. New class with all necessary methods, abstracting libetpan. Optionally stored in DCC database.
    Folders have their own class.
    • pro: reduced efforts for clients
    • con: more effort to implement now
    • con: more effort for DCC to migrate away from libetpan
  4. Extend the existing message class (dc_msg_t). Stored in DCC database.
    Folders can use either their own class or extend the existing chat class (dc_chat_t).
    • con: big change to existing APIs, code and DB
    • con: gets in the way / increases the learning curve for pure chat clients

Just counting the pros and cons, options 2 seems the best so far. But before we start thinking about implementation detail, what are your thoughts and ideas about it? Maybe some completely different implementation ideas?

2

Not sure this is a good forum for discussing what are rather implementation APIs and architecture questions. I’d rather suggest the mailing list. Let me still say a few things :slight_smile:

I suggest to think more about the needed API and not too much about how it’s implemented. There is a lot of tentative/incremental flux that could happen in the next months, regarding moving code from C to Rust etc. And let’s maybe first talk about sending/receiving semi-arbitrary mime-mails, not about new/added IMAP handling. Which C-API would be needed and how would it work/be specified?
How does Autocrypt-handling happen including encryption and decryption? If mime-mails are not tied to a chat at sending time, but to a caller-specified list of recipients, then how are they accessed on the receiving side?

3

I created a thread on the mailing list (archive link).

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