Help Problems with IMAP/Exchange


I have a Dell Streak which runs an older version of Android, dunno which.
I have setup GMAIL in the gmail app, that works fine.
I have also setup IMAP to google apps in K-9 email, works fine.
But I cannot get IMAP to my exchange mail to work in the default mail app or K-9. The settings are correct as they are the ones I use in outlook, but it keeps telling me my login details are incorrect.
I have tried setting up a native exchange mailbox, also does not work.
My wife has a HTX desire and ha sthe exact same problem, other IMAP aco**** work fine, not exchange, what is the difference?