Why do I get the ‘Unable to send email. Contact the site administrator if the problem persists’ error when saving content?

This error occurs from the workflow notification module when you test in a local machine or Cloud IDE. Cloud IDEs and local dev environments, such as DevDesktop, DVM, and Lando, do not have a mail service installed at this time. You should test this feature in Drupal Starter Kits while hosted in Acquia Cloud. If you receive this error in Cloud Platform, proceed with troubleshooting the inability for Drupal to send email.