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:

NOTE:  The above method/setting shall be only workable with Exabytes mail server and not referring to external mail server.