Simple Java Mail SMTP host

I am using Simple Java Mail API in order to send emails from my Spring Boot application. The app's owner was my colleague who doesn't work with me now. In my application.properties file I have the following config

simplejavamail:
  smtp:
    host: 172.28.94.229
    port: 25
  javaxmail:

The question is that I can't understand what host is this? Which server my emails go to? Is this something provided by Simple Java Mail, but I couldn't find anything in their documentation.

This IP address is not publicly routable on the Internet but is reserved and used for private or local networks. For you information the following IPv4 address spaces are not Internet routable:

• 10.0.0.0/8 IP addresses: 10.0.0.0 – 10.255.255.255
• 172.16.0.0/12 IP addresses: 172.16.0.0 – 172.31.255.255
• 192.168.0.0/16 IP addresses: 192.168.0.0 – 192.168.255.255

You can try the following command

telnet 172.28.94.229 25

and see if you get a timeout (meaning that no service is listening on that IP/Port) or you are connected to some service.

If this IP/Port exists and you get a connection opened, then you should ask your company's system admin for more information on that SMTP server. If you cannot get connected, maybe this is just a mock / not real SMTP server.