Outlook is operating like POP though it is set up like IMAP. Emails are being deleted automatically on iphone, Macbook pro and mail server

I set-up Outlook using IMAP (and used the IMAP setting on my iphone as well).  I have 2 issues:

1) The only way I can view emails (received/sent) on my Macbook Pro is to click on My Computer or INBOX

2) The only way I can view emails (receive) on my iPhone is to select all email accounts

Our mail is hosted by YOURHOST.COM and if I view my emails directly on the server account, I can see only about 150 of the 7000 emails I have on my Outlook (when viewing emails on in my INBOX).  These same 150 emails match exactly the same emails if I click on the email account I set up on my MacBook and as well as the 150 if I view only the email account on my iphone.

I sent a test email to my email account.  It showed up immediately on my iphone, on my Macbook and on the mail server.  But after about 1 minute, it was automatically deleted from my iphone and the mail server.  I can also, only view the test email on my iphone by clicking on my INBOX or ON MY COMPUTER.

I am not running this outlook account anywhere else except on my iPhone and MacBook Pro.  

I am using OSX 10.6.8 and version 14.3.9 of Outlook for Mac 2011.

Hope someone can help me; I've been to the Genius Bar 5 times and on the phone with YOURHOST about 15 times.  Apple advised me today that it seems like my Outlook is operating like a POP account; however it is set up as IMAP.