Adds a listener's email address to a soundcast's invitee list, and sends an email to the listener with instructions to access the soundcast. If the email address is associated with an existing listener account on Soundwise, the listener will be automatically subscribed to the said soundcast. If the email address doesn't have a Soundwise account yet, the listener will be subscribed to the soundcast as soon as they create an account on Soundwise using the same email address. If the soundcast subscription is renewed periodically, the listener's subscription will be updated when their next subscription period starts.

Remove a listener's access to a soundcast.