you probably know to setup all emails to go to Inbox by Sven suggestion:
Go to Options => More options... => Rules for sorting new messages => Click New => Set that senders address contains @ and move to inbox. => SAVE
Now, here is one more thing that you may wish to do in order to get emails REALLY deleted, as by default they are left on server...
Go to Options = > POP and deleting downloaded messages => Select "Do what my other program says..." => SAVE