SMTP (Simple Mail Transfer Protocol) manages the email sending.
Basically, it allows you to deliver the messages by the remote server.
There are two critical features to help email services: SMTP and POP3. They enable the user to send outgoing mail together, respectively, and to collect incoming mail.
If you use an email client, the SMTP server environment will need to be configured to allow you to send outgoing messages.
NetHunt SMTP allows you to send out unlimited email campaigns avoiding Gmail/GSuite limitations.
It has been set up for you already. Currently, this feature is free (fees will be applied in the future), however not available in trial (paid subscription only).