If you'd like to grant access for someone else to be able to view and manage your email Inbox, Google allows you to delegate that access to another SNC account. A typical use for this is when a secretary needs access to their boss' email Inbox.
Specific information on how to add or remove a delegate is available in this article:
Note that for security reasons, the ITS Service Desk cannot grant this access. So if you need access to someone else's account, please just ask them to grant it.