JavaMail MessagingException: SSLHandshakeException - No Appropriate Protocol

This exception occurs when JavaMail encounters an issue sending a command to the SMTP host. The nested exception, 'javax.net.ssl.SSLHandshakeException: No appropriate protocol (protocol is disabled or cipher suites are inappropriate)', indicates a problem with the SSL handshake.

The 'No appropriate protocol' error suggests that the required protocol for the SSL handshake is disabled, or the cipher suites being used are incompatible.

To resolve this issue, consider the following steps:

1. Check the SMTP server's SSL/TLS protocol: Ensure it's enabled and compatible with your JavaMail version.
2. Verify the SMTP server's cipher suites: Confirm that your JavaMail version supports the server's cipher suites.
3. Update your JavaMail library: Newer versions often include fixes and improvements for SSL/TLS protocols and cipher suites.
4. Custom SSL context: If you're using a custom SSL context, ensure it's configured correctly with appropriate protocols and cipher suites.
5. Upgrade Java: If using Java 8 or older, consider upgrading to a newer version for better SSL/TLS support.

If these steps don't resolve the issue, contact the SMTP server administrator for further assistance.