Users on your web portal receive email notifications of new statuses on ideas they create or vote on by default.
When capturing feedback from a customer in the Contributor Sidebar, Salesforce Sidebar, Zendesk widget, etc., you have the option to subscribe the user to all future status updates. You can update a user's subscription in the future by clicking "edit" under the feedback, and selecting the box next to "Subscribe user to future status updates".
Note: Any user has the option to disable status updates email notifications universally.
It is not recommended to unsubscribe from status updates through email, as this will unsubscribe you from all UserVoice emails. Simply update your email notification setting by deselecting "Status updates" through settings.