At the moment, users cannot configure notification sending with several recipients in one email (via "To"). This problem can be solved if we allow to the user to specify several emails separated by commas in the media.sendto field. Email will be created according to the same rule "1 media = 1 message", but with new functionality in 1 media can be included several recipients. This will reduce the number of meaningless media and simplify the configuration of alerts.
Update: Multiple email addresses in front-end sendto field must be specified one per row. Using API interface, sendto field requires an array, but a string with single email address will be accepted as well.