You can grant access to your Gmail account by adding a delegate. This person can read, send, and delete messages for you.
Add a delegate:
You can add up to 10 delegates. If you're using Gmail through your work, school, or other organization, you can add up to 25 delegates. There's no limit to the number of accounts you can be a delegate for.
- On your computer, open Gmail. You can't add delegates from the Gmail app.
- In the top right, click Settings
.
- Click Settings.
- Click the Accounts and Import tab.
- In the "Grant access to your account" section, click Add another account. Note: If you’re using Gmail through your work or school, your organization may restrict email delegation. If you don’t see this setting, contact your admin.
- Enter the email address of the person you want to add.
- Click Next Step
Send email to grant access.
The person you added will get an email asking them to confirm. It may take up to 24 hours for you to see them as a delegate after they confirm.
Note: The invitation expires after a week.
Remove a delegate:
- On your computer, open Gmail. You can't set up delegates from the Gmail app.
- In the top right, click Settings
- Click Settings.
- Click the Accounts and Import tab.
- In the "Grant access to your account" section, click Delete next to the account you want to remove.
What your delegate can do
Delegates can do things like:
- Send or reply to emails that were sent to you. When they send a message, their email address will show. For example, the sender will show as "sent by johnsmith@gmail.com."
- Read messages sent to you
- Delete messages sent to you
- Manage your contacts
Delegates can't do things like:
- Chat with anyone for you
- Change your Gmail password
- Change your Gmail account settings
<source: https://support.google.com/mail/answer/138350?hl=en>