deleted mail disappears


In Mail 2.0.2 under OS X 10.4 mail I delete disappears straight away and never appears in my deleted mail folder. I don't remember having set Mail to do this nor can I see how do unset it. Can anyone help? Tony.
In Mail's Preferences, under the Accounts>MailBox behavior you can set it up the way you want it.
Unfortunately I can't. Resetting the deleted mail options makes no difference; whatever I do the deleted mail folder is empty as soon as mail is deleted and there are no files in /users/user/library/mail/mailboxes/deleted messages.mbox
Move the mail.plist file to the Desktop and try, located here;