We have an additional web front end setup, that includes access from outside of the network.
How can I set the URL inside of the alert emails to be redirected to the additional web front end instead of the primary poller?
If I'm reading your question right, then this should give you the information you need:
Configure website URL for Alerts and Reports - SolarWinds Worldwide, LLC. Help and Support
thank you!
Credit to Neomatrix1217 for supplying the answer when I asked a similar question:
How to change the URL variable in alerts to publish a different name?