Are you looking to send a message when the job completes normally, or are you looking for when the job is ended abnormally?
You can use the internal SMTP server if your Midrange has access to the outside via your network.
Make sure you check your release level and make sure your PTFs are up to date so you don’t run into any weird issues trying to use the SMTP server.
You will need to become familiar with the MONMSG (Monitor Message) command and the SNDDST (Send Distribution) command in addition to configuring for SMTP.
Hope this helps,