Don't sell an email client, there is a reason they are all dead: too much effort, too many edge cases (POP3, IMAP, Exchange, Gmail...), not enough margins.<p>Instead, sell me <i>a hack that can make Outlook look like that</i>. You worry exclusively about the UI, Microsoft does the heavy lifting behind the scenes.<p>Best case: you make a ton of money by selling to actual businesses (rather than annoying geeks and other weirdos who dare use uncommon clients); slightly-worse case: you sell it to MS.