Navigate to [https://admin.google.com/ac/apps/gmail/usersettings](https://admin.google.com/ac/apps/gmail/usersettings)

Look under "Mail Delegation" and make sure it is turned "ON". If you click the pencil icon, you can edit further details.

Now you're done! Here's a Scribe that shows your users how they can delegate their inboxes to others, now that you have set their permissions to on : 

Google Admin

Gmail

Google SSO

Google

In order for users in your company to be able to delegate their email accounts (say, to share with an assistant), you need to have a global setting turned on so they have permissions to do so. This Scribe shows you how.

How to Enable Users to Set Email Delegate Permissions in Google Admin