Hello,
in outlook you have to configure the email account as IMAP, not POP3.
this must be done manually when setting up the account
but i warn you, outlook in all it's versions, is really bad at handling IMAP. as example: if you try to make an outlook inbox automatic filter, that moves all from the imap inbox to a local inbox folder... it will sometimes work... but most times it won't
this is how i make it work "my way":
1) set up the email account normally, as pop3, receiving all mails into the local inbox (the infamous .PST file)
2) set the account up AGAIN, call it something like bla bla (IMAP)
3) make sure all sending and receiving is done through the regular default account
4) users can now copy/move stuff from the local default folders to the imap folders and viceversa
i hope i explained myself well enough.
PS: instead of outlook you could try thunderbird. it will need some work (plugins) to look as pretty as outlook, but it works with IMAP perfectly
S.