org.springframework.mail.MailAuthenticationException: Authentication failed; nested exception is javax.mail.AuthenticationFailedException: 534-5.7.9 Please log in with your web browser and then try again. Learn more at 534 5.7.9 https://support.google.com/mail/?p=WebLoginRequired v202-v6sm20135393oie.47 - gsmtp

org.springframework.mail.MailAuthenticationException: Authentication failed; nested exception is javax.mail.AuthenticationFailedException: 534-5.7.9 Please log in with your web browser and then try again. Learn more at
534 5.7.9  https://support.google.com/mail/?p=WebLoginRequired v202-v6sm20135393oie.47 - gsmtp

Google prevent it for security purpose..

Click on this link:https://www.google.com/settings/security/lesssecureapps

you will see turn off or turn on. Click "Turn on"

Then try your code again it will work, worked for me