Subscribe to get email notifications for a Label
(string) LabelNumber (Required) - The label number subscribe to.
(string) EmailAddress (Required) - The email address to receive notifications.
(string) CountryCode (Rquired) - The code of the country in which the label resides.
See here for a list of valid country codes.
Successfull call will return 'True'.
https://nz.api.fastway.org/latest/tracktrace/subscribeemail/3A0000253492/joe_blogs@email.com/1?api_key=YOUR_API_KEY