Enable to connect to SMTP server.  Please check the configuration details provided.

Refer below screenshot :

Please check the below setting in your google account before configuring SMTP-

Turning on 'less secure apps' settings as mailbox user-

1. Go to your (Google Account).
   
2. On the left navigation panel, click Security.
   
3. On the bottom of the page, in the Less secure app access panel, click Turn on access.
   
4. Click the Save button.