Based on your screen shot, it looks like you are just using random credentials? You must have a functional SMTP server connection in order for this to work. There are many different alternatives (Google, Amazon, self-hosted, etc) with different pros and cons.
Regardless of the route you chose, you will need working credentials on a server in order for it to work in DHIS2.
If you want to use the google mail server, you have to specify smtp.googlemail.com (smtp@gmail.com is not a correct format for a mail server, but for a email address!)
Then you have to specify a valid username for the specific mail server - in case of free gmail account, it have to be something as mygmail@gmail.com with the relative password or better Password for App to comply with the latest safety requirements.