I think Gmail has much more than 5% of the market. It may be that Outlook is installed on 35-45% of all computers, but nobody currently has numbers for the use of the application. If I can get away with it, I prefer forwarding mails so I don't have to deal with Outlook.
And so should all sane companies: Outlook waste their time.
And so should all sane companies: Outlook waste their time.