If you use the report function, to receive daily a report by email with all emails processed, you must set the properties to send an email, called SMTP.

If you use Gmail, O365 or another well know email providers, the settings will be set automatically. If you use your own domain you have to enter the mail server address, login and password.

SMTP server address: Generally under the form mail.YOURDOMAIN.com or smtp.YOURDOMAIN.com 

You can test the settings by sending a test message, click on 'Send a test message'.