Does this happen - all the time, some of the time, is there a pattern?
Where are the mailboxes (I see that one is @centrum.cz, what about you @Nigelmay, GoDaddy by any chance)?
Both message view and message list end up calling same code to mark read / unread and sync back to server.
I remember a case or two like this, one fairly recent, and it turned out to be a server bug.
The difference (message list / message view) is that when you reply to a message, Aqua sets the "replied" indicator (a small arrow) on the original message. In one case I remember, this was causing the mail server to also mark the message as unread.
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But that doesn't help you and also doesn't tell us anything.
What would be best is if you could:
- Answer my questions above (all the time, some of the time, is there a pattern)
- Capture the issue, start to finish (from receiving a message to doing whatever to it turning back unread) in the app's debug log, with "raw session data" enabled. Please see the link in my signature for that.
- Send the logs to support / aqua-mail / dot com
Thanks