How to Delegate Your Inbox

In Gmail, activate the gear icon in the upper right and then "See all settings."

gmail settings

Choose the Accounts tab.

gmail accounts tab

In the Grant access to your account section choose "Add another account."

add account

In the pop-up window, enter the address to which you would like to grant access, and then confirm...

grant access

(Access can only be granted to other BSC accounts)

And when the other account accepts the invitation they will have complete access to your inbox as well as most of the configuration settings in the accounts menu. But not Drive documents. If you want to share documents between accounts, Shared Drives are your best choice.

More information about Shared Drives

More information about account delegation in Gmail