Allow Relay notifications to include manually entered email addresses instead of limiting the list to existing collaborators
Currently the Relay system will only allow notifications to be sent to existing collaborators or users. There should be a way to allow any manually entered email address to be a notification destination. This would allow for group or shared email accounts to be a notification destination. Group email addresses or shared email accounts may not exist as specific collaborators but still could be useful for notifications.
Additional use case would be to notify an uploader that a piece of content has been approved by an organization. Marketing use case using an external agency receives an email stating the internal team has approved the content.