Deleting Email Messages
You can delete email messages from the email source after they have been saved to disk. You need to enable the delete option both at the source and at the target. The messages will be sent to the Deleted Items folder or to the Trash folder depending on the email client that you are using
1. Select the "Delete email messages from the email source" at the options tab in the source dialog.
2. Enable the "Delete messages" at the Single Files target: