Microsoft Mail and Calendar
Mail and Calendar apps already built in Windows 10.
Windows 10 has Mail and Calendar apps already built in.With the Mail application you can now easily see all message from your favorite people, more clearly organize social updates and newsletters, and use the popular “Sweep” feature to clean up your inbox.
UI is good, but that the only thing is good.
Ui is great.
Low level feature. Also some mails doesn't show attachments
[Edited by ugurozturk, September 16,2018]
It turns out that Windows 10 Calendar is very limited in the events it can show. It won't display events older than 3 months, and if you have a Google Calendar or iCloud account it won't show events more than 6 months into the future. The workaround is to use the website versions of your calendar instead... but if I wanted that, I wouldn't be using the Calendar app or a Windows computer. Unfortunately I still haven't found a calendar app for Windows that is as good as Apple's iCal / Calendar program.
Very good ui, but they missed some major features and never update the bugs out. For example, there is no way to make a HTML signature in this app, and the calendar is unreliable.