Webhooks offer a far more efficient way to monitor changes to an endpoint than traditional polling. In this recent article on InfoWorld, Mark Geene discusses the technology and highlights three commercial implementations that put it to good use to improve the customer experience.
Email, which is one of the oldest services available on the internet, is a key mechanism via which you can reach out to your users. Over the last year, the number of services providing this infrastructure as a service has grown to include 6 email sending APIs. The newest, Amazon Simple Email Service, validates the market.