Email access
To grant someone access to your mailbox, you will need to switch back to Classic Outlook by clicking the New Outlook toggle in the upper right.
According to Microsoft official documentation, "Currently, assigning delegate permissions to mail folders in new Outlook is only partially available. You can still have delegates, but you must use classic Outlook to assign those permissions first."

Calendar access
Quick guide
- Click the Calendar
tab.
- Right-click the calendar you want to share, and select Sharing and permissions.
- Search for and select your delegate.
- By default, the delegate's permission level is set to Can view all details. You can change this.
- Click Share.
- The delegate now has calendar access, and receives a sharing invitation via email.
Detailed guide (with screenshots)
- Click the Calendar
tab.

- Right-click the calendar you want to share, and select Sharing and permissions.

- Search for and select your delegate.

- By default, the delegate's permission level is set to Can view all details. You can change this.

- Click Share.

- The delegate now has calendar access, and receives a sharing invitation via email.
