Hi there,
the problem is usually the mail server that you are using. I saw in the screenshot that you are using GMAIL servers? GMail server work with encrypted authentication and it's not easy to send an email through them. you should check the Java Mail APIs in order to be able to connect more advanced mail servers. If you install your own mail server on your computer it will probably work in the way that you configure it but for third party and secure server you will require more advanced configurations. This is not a jBPM5 problem, it's just a Java + Emails configuration that are requiered for every Java Application.
Hope it helps