What is a regular expression to validate only work emails in JS (declining free email services such as Gmail)? [duplicate]

What is a regular expression to validate only work email addresses in JavaScript (declining free email services such as Gmail, Yahoo, Outlook.)?

I have written the pattern = /^[^ ]+@[^ ]+.[a-z]{2,3}$/; to validate free email addresses but I don't know how to validate only work emails

Here's my code:

// validate email address
var email = document.getElementById('email');

function validateEmail() {
  var emailValue = document.getElementById('email').value;
  var pattern = /^[^ ]+@[^ ]+\.[a-z]{2,3}$/;
  if (emailValue.match(pattern)) {
    email.classList.remove("is-invalid");
  } else {
    email.classList.add("is-invalid");
  }
}

email.addEventListener('keydown', validateEmail);