I have Opera Mail.
My email accounts are all IMAP.
The online tutorial says to go to EDIT ACCOUNT SETTINGS, then (1)open INCOMING and (2) check the relevant check boxes to: leave or store messages on the server.
However, when I select INCOMING there is no check box for leave or store messages on the server.
ABout Opera says:
SO how do I make sure I clear the messages when I download them. I keep getting Critical messages about the mail on the server.