Office 365 (Outlook Client for Windows) - Allow Someone to Manage Your Calendar and/or Email (Assign a Delegate)
Similar to having an assistant that helps you manage your incoming paper mail, another person, known as a delegate, can receive and respond to email messages and meeting requests and respond on your behalf. You can also grant the delegate additional permissions to read, create, and/or change items in your Microsoft Exchange Server mailbox.
Delegate Access goes beyond just sharing access to your folders. Delegates are granted additional permissions, such as creating email messages or responding to meeting requests on your behalf.
As the person granting permission, you determine the level of access that the delegate has to your folders. You can grant a delegate permission to read items in your folders or to read, create, change, and delete items. By default, when you add a delegate, the delegate has full access to your Calendar and Tasks folders. The delegate can also respond to meeting requests on your behalf.
For the most current information on assigning a delegate, please see the following Microsoft Office support article: https://support.office.com/en-us/article/Allow-someone-else-to-manage-your-mail-and-calendar-41C40C04-3BD1-4D22-963A-28EAFEC25926.