Reason
On networks under certain restrictive governments and workplaces, only a small set of classic mailbox providers are allowed. Some of these have a declared rate limit for mail sending and reception.
Others do not declare such a limit, but may be operating heuristic spam filters that will tend to catch messages in groups above a certain size or beyond a certain posting frequency.
Features ´
Only chatmail accounts and the bot account would be present in the open group. Restricted users could participate by opening a direct message with the bot for it to relay messages from and to the open group. As an implementation detail, efficiency could be improved by using a single combined channel for reception and private messages for individual replies.
The bot would collect messages from the open group and only send it in private in larger batches delayed and combined temporally and preferably per sender.
The batching interval and heuristics could be adjusted based on a selected target sending rate. In times of low traffic, each message could arrive individually within a minute. At other times, two or three consecutive messages of the same user could be sent as a single message.
It is to be determined how the batches should be formatted, but ideally each individual snippet should be delimited by a marker and preceded by a header mentioning the sending user, the timestamp, whether it is a reaction emoji, and possibly a readable form of which message this is a reply to (if different replies needed to be combined in a single batch). Such reference links could be visualized based on the timestamp and possibly by the raw message ID.
Optionally, the group could also be accessed using a webxdc interface that would render individual snippets inside batches seamlessly as if they were individual messages. This could also enable limiting the sending rate of the restricted user by generating similarly formatted outgoing batches.