Outlook sent emails not in sent folder on server iPhone

My iPhone is using IMAP. My Outlook 2010 is using POP3. When I send an email from my iPhone or from the web based mail on the server, they both show up in the sent folder on the server.
When I send mail from Outlook, the sent mail does NOT show up in the sent mail folder on the server (and therefore does not show up on my iPhone). Also, the sent mail on the server does not show up in the sent folder in my Outlook (so the sent mail from my iPhone does not show up in Outlook). Is this because Outlook is set as a POP3 account?
I had a devil of a time setting up a reliable email account on my Outlook a couple years ago, so I am nervous as **** about changing any mail parameter in Outlook, but I would sure like to see all my sent mail on both my iPHone and my Outlook.
Suggestions???
Dell D830 Windows Vista Outlook email sent