Watch this video to setup as many SMTP email servers as you want. And, then add as many Email Notification Nodes into your decision tree as you want.
When Using Google or G-Suite
Please note: Google security will give issues since LeadsHook IP address will be different when accessing Gmail or G-Suite mail servers.
So please be sure to create a new App Password for LeadsHook.
App password feature is NOT visible until 2-step verification is also activated. (More in the video above):