None of the above works for me. I am running Android 4.4.4 on a new Nexus 7 tablet. I have the email set up for a third party server. I have discovered (to my dismay) that when I delete an email from my tablet it deletes it from my server making it impossible to recoup it. When I go to Settings>accounts>imap there is no option to leave messages on server anywhere that I can see. Also if I go to incoming messages as suggested above, there is no option to leave mail on the server. There is the possibility to never sync but I don't know if this will solve the problem or not.
Does anyone have a suggestion about this?
Of course, I always have the option to wait till I get to my computer to delete stuff but this leaves a lot of mail on my tablet.