1. Login into your WordPress admin portal via domain.com/wp-admin

2. Navigate to Add New under Plugins 

3. Look for SMTP plugins such as SMTP mailer (https://wordpress.org/plugins/smtp-mailer/) or WP Mail SMTP (https://wordpress.org/plugins/wp-mail-smtp/)

4. Once it has been install, may navigate to the plugin settings from Setting (In my case, I will be using SMTP mailer)

5. You would need to ensure that the SMTP username is a legit/valid email on your hosting. 

6. Basic settings will be as below: