New Yahoo mail is already looking awesome, but I think few more things will make it more better, particularly Yahoo Calendar which I see well available on Desktop's web version, but not available neither on Yahoo Mail - Mobile (iOS/Android) app or Yahoo has a separate Calendar App like Google Calandar.

Today Calendar plays an integrated role in daily life planning, and Yahoo's calendar's incompatibility to integrate seamlessly with iOS calendar or Android or macOS calendar actually keeps it disconnected from integrated one platform expertise.