The article isn't very honest here. Most people who use Microsoft Outlook for email are doing it in the work environment and utilize Microsoft Exchange server to form a complete enterprise email solution. The alternatives offered are merely desktop email clients mainly for use as front-ends to SMTP/POP/IMAP servers or web-based email services offering such services. Not many people are using Outlook solely as a desktop email client or away from a work environment. While the Evolution email client does support Exchange server integration, the best it can do if half-free you from the Microsoft email ecosystem. The other two alternatives given aren't really any competition for the Microsoft products in a business unless that business is small and email isn't critical to its daily operations. I have yet to see a viable competitor in that realm since Lotus Notes and that was a long time ago now.