This chapter demonstrates how to send and receive e-mail on the Google App Engine. First, it shows how to send a full-featured e-mail with HTML markup and an attachment. Then it shows how an application on the App Engine can receive e-mail and store it. Google offers two APIs to send e-mail: the JavaMail API and a low-level API. While presenting examples, this chapter draws a comparison between both APIs.
An App Engine application can use e-mail for many purposes:
• Notify users when changes are made.
• Store details that are hard to remember in the user’s mailbox.
• Deliver electronic products.
• Authenticate website visitors for low trust levels.
• Reach website visitors after they leave the site.