To make it clear, nobody talks about removing support for non-chatmail servers, they are supported. What we want to get away from is sharing mailboxes (identified by the email address) between Delta Chat and email clients that don’t understand chat messages.
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Reordering problems. There is no order between messages in different folders, messages only have order within one folder, so you need to move messages from
INBOXtoDeltaChatbefore processing them and only read messages fromDeltaChatfolder. Otherwise your devices may process messages in the wrong order as one of them is reading fromINBOXwhile the other has already read the message fromINBOXand moved it toDeltaChat. To move messages toDeltaChatfolder before downloading you need to know if it is a chat message and the only way to know it is to have aChat-Versionheader unencrypted. We want to encrypt theChat-Versionheader as a part of the effort to reduce metadata. There are also issues with some providers that don’t supportMOVEcommand or support it but don’t advertise it in which case you need to resort to copying and deleting fallback and this causes reordering when you have multiple devices. -
Watching multiple folders requires maintaining multiple connections to IMAP server.
(There is an IMAP NOTIFY extension, but it is not always supported so we cannot depend on it. Adding more dependencies like this is a problem for developing new servers, e.g. we recently removed the need to haveCONDSTOREextension.) Some providers limit the number of connections per profile so it is possible to end up in a state where connection toINBOXworks but connection toDeltaChatfolder does not and vice versa. This status needs to be displayed in connectivity view where we now display multiple relays as well. -
Notifications. If Delta Chat is used to move messages from
INBOXtoDeltaChatfolder, you will often get a notification when the message arrives intoINBOXand before Delta Chat moves it toDeltaChatfolder. -
Requirement to keep Delta Chat running. Since it is the client that keeps chat messages separated from non-chat messages, if you remove a profile from Delta Chat or uninstall Delta Chat or simply have it on a device that is currently offline, you will still keep getting chat messages into the same inbox from contacts that don’t know you don’t use Delta Chat with this address, and the messages cannot be separated anymore. You may be traveling with Delta Chat installed only on your desktop, you open webmail client and it is full of encrypted chat messages from some group you are in.
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Latency. Each message first comes into
INBOX, thenINBOXloop gets notified, stopsIDLE, lists messages in the folder and moves the message toDeltaChat, thenDeltaChatgets notified, stopsIDLE, checks messages in the folder and fetches the messages. Same for push notifications, on iOS ifDeltaChatfolder is used, when push notification arrives you need to first checkINBOX, then only onceINBOXis fetched and all messages are moved fetchDeltaChatto see what UIDs got assigned to them and fetch them.
Support for non-chatmail servers and plaintext email is not removed and there are no plans to remove it. You can use Delta Chat to receive notifications about plaintext emails and reply to them, nothing changes about it. But for encrypted chatting we want to avoid users setting up new profiles with the same mailbox they already use because this results in all the problems listed above and was never a nice experience.
For new users: if you have your own server and want to use it, it can be done, just create a new mailbox for chatting and create a new profile with this mailbox without reusing existing one. If you want to use Delta Chat to also read messages from existing inbox, just setup another profile and receive messages there, but use dedicated profile for chatting.
Unless you use 10 classic email profiles for chatting as 10 different profiles in Delta Chat, disabling moving to Delta Chat folder should not be a problem for most of them.