Gmail is the email solution of choice for a huge number of Netizens, and that provides a rich playing field for developers hoping to be useful to you by providing tools that simplify email overflow.
Enter Google with its latest endeavor, "Inbox." From Engadget:
If you're anything like us, Google's Gmail has an iron grip on your life. Google's looking to create a whole new iron grip with a new app from its Gmail team, and it's called "Inbox." What is it? That's a good question -- Google's made a demo slash advertisement video that we've dropped below. As far as we can tell, Inbox is a combination of Google Now and your Gmail inbox -- a "smart" inbox, if you will. It combines alike pieces of email (bank invoices, for example), highlights related information (like Google Now alerting you to flight changes, traffic, etc.) and keeps track of your life (it'll give you reminders, among other heads ups). Is this the end of Gmail? We seriously doubt it, but it is Google's latest foray into simplifying email.
I don't need calendaring or messaging data. A pure email solution via IMAP is perfect for me. Access under Linux: Claws Mail. Under Android: K-9 Mail. Under Windows... erm... don't need mail to start my games.
But I bookmarked the project page. Should I ever need groupware features, I now know it exists. However, should I ever install it, it most likely will be for other people. For me... I deeply distrust such universal-all-in-one-super-duper-everything gadgets. Open source or not.