It is a concern close to “force sync old messages”.
I received some “unreadable” messages in Delta.Chat. It was legitimate messages, from authorized contacts, but the retrieval process might have been cut (maybe by BatteryFu from f-droid.org, that I use on Android to poll the internet and save battery life). Next messages from those contacts were received and read well.
I would like a “retry receiving this message” menu entry in the details of those messages.
(For the record, I got those messages in my phone today because I installed the desktop client importing an old backup, having it imaps-reading months of old messages, including those legitimate messages that poped up in my phone also (!?) in a non chronological order with no way to sort the discussion again in chronological order…)