Answer : To configure SMTP email system, change the following features from your gmail account.

1. Log in to your gmail account and go to 'My Account' by clicking on the image of top right corner.

2. Click the Sign-in & Security tab.

3. Turn off the 2-step verification feature from Sign in to Google section.

4. Turn on Allow less secure apps from the Connected Apps & Sites section.

After making these changes from your gmail account, go to your Admin panel and follow these steps:

1. From the navigation, go to Frontend Setting → Site Settings → General Settings.

2. Click on the Smtp Settings tab.

3. Fill up the form as below:

                     Smtp host: ssl://smtp.googlemail.com

    Smtp port: 465

    Smtp user: YOUR GMAIL ID

  Smtp pass: YOUR GMAIL PASSWORD

      4. Click on the save button to save the changes.

 * If you have any problem, first check to make sure you’re using the right password.

* If the tips above didn't help, visit https://www.google.com/accounts/DisplayUnlockCaptcha and follow the steps on the page.

[ N.B: Sometimes it takes more time than usual to send mail, if the receiver is using other account but not gmail account. ]