title: How to restrict email domains in Firebase Authentication
body: <p>I have a question regarding firebase authentication. Actully I am making a dashboard for my company, and I will host it in firebase. I want to restrict the email authentication only to my comany domain (ex: cat.com). But I went through the stackoverflow answers and I found I can impose rule in database. But the issue is that I will be calling external databases to fetcj data using Firebase Function and serve it to website(dashboard). So no domain specific rule will apply there. Below is the outline of my dashboard architecture</p>
  <p><a href="https://i.stack.imgur.com/y9RhN.png" rel="noreferrer"><img src="https://i.stack.imgur.com/y9RhN.png" alt="enter image description here" /></a></p>
  <p>How can I achieve this? I want people having &quot;xxxx@cat.com&quot; will be able to autheticate and view dashboard data</p>