Java 7 runtime support on App Engine standard was deprecated on December 13, 2017 and will be shut down entirely on January 16, 2019. It is replaced by the Java 8 Runtime Environment.

Samples for the Java 8 runtime can be found here.

This sample demonstrates how to use JavaMail on Google App Engine standard environment.

See the sample application documentaion for more detailed instructions.

1. Update the <application> tag in src/main/webapp/WEB-INF/appengine-web.xml with your project name.
2. Update the <version> tag in src/main/webapp/WEB-INF/appengine-web.xml with your version name.

$ mvn appengine:devserver

$ mvn appengine:update