Hi, the exception is clear
Caused by: javax.mail.MessagingException: Could not connect to SMTP host: smtp.gmail.com, port: 465, response: -1
You are not even connecting to the mail server. I'm not sure if it's a good idea to use a public email server to do that.. probably they don't allow you to do that or you will need to set up all the authentications mechanisms required by google.
If you have an internal mail server that will work, but your problem now is the connection with the mail server.
Cheers