How to set up Gmail SMTP?

In Setting > SMTP configuration, click New in the top right of the screen to set up a new SMTP use for sending email.

Fill out these fields to complete the set up:
User name: User’s Gmail address that used to sending email through Realcore, ex: realcore@gmail.com
Host: smtp.gmail.com
Port: 587
Password: This is not your Gmail’s password, to get this password, follow the guideline here: Sign in with App Passwords
To be simple, you will create a password that used for just Realcore, make sure you turned on the 2-Step Verification of Google account.