Hi Joe,
Thanks for taking the time to reach out! While there’s no built-in way to specifically limit RSVPs or ticket purchases to certain domains, you may be able to achieve something similar by restricting your RSVPs to registered users only. By enabling this setting and only allowing users on certain domains to create user accounts, you can limit your RSVPs by whatever criteria you’d like. You can learn more about this setting, as well as all other settings available with Event Tickets and Event Tickets Plus, on our Knowledgebase here:
https://theeventscalendar.com/knowledgebase/configuring-event-tickets/
I hope that helps to get you on your way here! 🙂 Thanks again, and let us know if you should have any other questions!