Unfortunately, old Outlook got too many things right.
This is not saying old Outlook is great. It's not. But it had some major wins that the FOSS community does not seem super-interested in replicating:
1) ActiveSync. Yes, it's a horribly-designed protocol. We complain about spaghetti code, and it's the next level of bad: a spaghetti standard. But what it does is insanely important: it gives end-users a really easy way to connect their email account(s), calendar(s), address book(s), and notes via a single, simple process that uses an autodiscover mechanism to minimize the number of things they have to enter. For normies, this blows away every other system out there if you want on-device, app-based processing and not a web site.
2) The user interface is livable, in a meh sort of way. But for normies, most of the other email clients out there are worse. Combining email, contact management and calendaring in one app, with good multi-calendar support was a great move. These things are all tightly linked, and having them together is super-convenient for end-users. Even Apple manages to screw this up badly. There are some decent commercial email clients out there, but getting people to pay more (overall) than Outlook is a very big ask in most business environments. The closest thing in FOSS is Thunderbird, and I try it occasionally and then delete it after a few months of frustration. Maybe I'll give it another shot now.
Biting the hand that feeds IT
