Do I need squirrelmail for Outlook to work?

The reason for the three mx records is that I am trying whatever I can think of plus what you are giving me to get this fixed. And yes I have created the email address under mailboxes and also the email domain. But does the email domain need to be closed out like in the DNS zones? If so that might be the problem. Is there a particular MX record I should keep or keep them all?