IMAP Server Deletes Emails from Trash Folder Automatically

I have been using Outlook 1013 with Windows 8.1 to receive emails in my Cox account for the past month. I have found that emails are automatically deleted (overnight) from my Trash folder two days after they have been deleted from my Inbox folder. If I disconnect the internet line from my computer overnight, the emails are in the Trash folder in the morning and are not deleted until the internet connection is reestablished, which indicates that the IMAP server is deleting the emails rather than Outlook 2013 itself. Microsoft technical support also confirms that Outlook 2013 is not deleting the emails. I have contacted Cox technical support, but they are unable to resolve the problem. Is there a solution to this issue? Thank you