1- Open Google and click the profile icon and “Manage your Google Account”. 

2- On the left side click “Personal Info” and search “App Passwords”. 

3- Type “App Name” and click “Create” and copy “App Passwords”.

5- Open Gmail and click on the settings icons top right side with the profile.  

6- Go to “Accounts and Import” come to the “Send mail as” sections and click “Add another email address” 

7- Type your “name” and “email address” and click on next.

8- SMTP Server: “smtp.gmail.com”
Port: 587
Username: Your Gmail address
Password: Your App Password 
and click “Add Account”