Natural HR has built in options and settings for triggering email notifications to employees and managers for Self Certification and Return to Work forms. For information on how to set these up, please refer to the article on this by clicking here.
By default, an email is sent to the employee's manager the day of the employee's return only. However you can choose to send an email to the manager every day until the relevant Self certification or Return to work process is completed.
To do this, go to
Administration > Company > Settings > Time off settings (global)
In the Absence settings section, select 'Yes' from the 'Return to work and self certification - daily email until completed' option