One of the most common issues in setting up PulseNET email notifications are the network security settings, including allowed ports and firewall rules.
In order to diagnose if the email server can be reached from the PulseNET server, external to PN itself, perform the following from an administrative Windows Powershell prompt:
telnet smtp.gmail.com 587
[Replace smtp.gmail.com in example above with required email server.]
If successful, the following response should be received with a "220" message:
Below is a Dell support link for additional reference on this issue: