Add New Address to gmail without SMTP (forwarding-only-address)

If you want to use an alternative email address instead of your original Gmail address, you need to provide details for an SMTP server, which will be used to send the mail.

The first action you should do is → Settings → Accounts → Add another email address, like below

Then you will see popup window like below

When you click “Next Step,” you will see the following:

If you have smtp server available, you can use it. Otherwise, please follow below

1. For SMTP Server, put smtp.gmail.com

2. For Username, your full Gmail address including @gmail.com
   Note that you should put your user account, including domain name, if you use personal domain name like foo.com

3. For password, provide an App Password generated in Google Accounts at https://security.google.com/settings/security/apppasswords
   The first action you should take is to put your application name. 
    

   

   
   In my case, I just use gmail-<domain name>. For example, if my domain name is foo.com, I just put gmail-foo.com like below:
    

   

   
   If everything goes fine, you will get your password like below:
    

   

4. Leave Secured connection using TLS selected as is.

5. Add Account