Oct 01 2020
When we creating Group in Microsoft Teams from scratch Mail App is missing but when we creating from O365 group Mail App is there. Why..?
Please refer below screenshot.
NormalGroup : This group is created from scratch and mail app is missing.
Created from scratch
M365Group : This group is created from Microsoft 365 Group and mail app is exist by default.
Oct 02 2020
Because Microsoft introduced a change a while back, "hiding" Team-ified groups from Exchange clients. You can "show" them via PowerShell: