COmanage Registry can use email to deliver invitations for enrollment and for notifications. By default, mail is configured to use CakePHP's MailTransport class, which itself uses PHP's mail() function.
You can change the default configuration via app/Config/email.php.
You can specify the mail From: address on a per-Enrollment Flow basis.
Support for further reconfiguration of mail delivery via the UI is planned. (CO-390)