"I think in the corporate sector, it would be very hard to dislodge Outlook, which is a shame really."
I'm not sure how hard it would be to take some Outlook Web Access share away if targeting smaller companies since the cost could be potentially lower and licensing agreements potentially much easier to understand.
Have you seen office365.com? $6 a month per user for cloud Exchange, web e-mail, full Outlook integration if you want, plus online storage, view and editing of Word, Excel & Powerpoint. It's a lot to compete with for $6 a month.
I'm not sure how hard it would be to take some Outlook Web Access share away if targeting smaller companies since the cost could be potentially lower and licensing agreements potentially much easier to understand.