test email is working but notifications do not send

test email is working but notifications do not send

how can i resolve this issue this is the error i am getting
javax.mail.MessagingException: Could not connect to SMTP host: smtp.gmail.com, port: 465, response: -1
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1949)

                New to ADSelfService Plus?