Appengine class not found javax.mail.address

A classic error!

The error "appengine class not found javax.mail.address" typically occurs when you're trying to use JavaMail (javax.mail) in a Google App Engine (GAE) project, but the App Engine runtime environment doesn't support it.

Here's why:

  1. App Engine's Java runtime environment: App Engine's Java runtime environment is based on the Google Web Toolkit (GWT) and doesn't support the full Java Standard Edition (SE) API. Specifically, it doesn't include the JavaMail API (javax.mail).
  2. JavaMail not supported in App Engine: JavaMail is not a supported library in App Engine, and you can't use it directly in your App Engine project.

To fix this issue, you have a few options:

Option 1: Use a different email library

You can use a different email library that's supported in App Engine, such as:

Option 2: Use a third-party service

You can use a third-party email service, such as Sendgrid, Mailgun, or Amazon SES, which provides APIs for sending emails. These services are supported in App Engine and can be used to send emails programmatically.

Option 3: Use a custom solution

If you really need to use JavaMail, you can try to implement a custom solution using App Engine's built-in email service (e.g., using the MailService API). However, this might require significant changes to your code and might not be as straightforward as using a supported library.

Remember to always check the App Engine documentation and the Java runtime environment's limitations before choosing a solution.