@PT - first, read messages should not be removed from AquaMail.
Second, since AquaMail syncs with the mail server and not with Outlook on your PC, let's check what's on the server.
Can you open your web mail and check what happens there when you delete messages in Outlook?
If they do get deleted in web mail, please do this:
- In AquaMail, long press the account, choose last item (Diag: message dates), let it run, mail me the log (when prompted at the end).
- Delete a recent message using Outlook, wait until the deletion syncs with web mail
- Repeat the first step, so I can get the "before" and "after" logs
Thanks