See Troubleshoot email on a new Discourse install.
A common problem is that the notification email is set to something that your smtp service won’t send from. It’s likely sending from noreply@your.forum and you likely need to change it to your email address.
But in the other topic you created for this problem you say
So your vm is blocking outgoing access to that port. Many services support port 2525 for this reason. You might be able to open a ticket and get them to unblock it.