SMTP throwing errors when trying to send email

Summary

Script is throwing errors when attempting to send email using SMTP.

I've tried installing net_SMTP on my server with PEAR, though I'm not familiar with PEAR so it's possible I didn't do it correctly.

Steps to reproduce

Try to send an email to someone directly via affiliates > email.

PHP version

PHP 8.0.16

What is the current bug behavior?

This error is thrown:

Fatal error: Uncaught Error: Class "Net_SMTP" not found in /var/www/aeipathy/enth/Mail/smtp.php:366 Stack trace: #0 /var/www/aeipathy/enth/Mail/smtp.php(271): Mail_smtp->getSMTPObject() #1 /var/www/aeipathy/enth/Mail/smtp.php(258): Mail_smtp->send_or_fail() #2 /var/www/aeipathy/enth/mod_emails.php(732): Mail_smtp->send() #3 /var/www/aeipathy/enth/emails.php(287): send_email() #4 {main} thrown in /var/www/aeipathy/enth/Mail/smtp.php on line 366

What is the expected correct behavior?

Email is sent