cal.diy/packages/features/watchlist/lib/checkIfFreeEmailDomain.ts

import { WatchlistRepository } from "@calcom/features/watchlist/watchlist.repository";

export const checkIfFreeEmailDomain = async (email: string) => {
  const emailDomain = email.split("@")[1].toLowerCase();
  // If there's no email domain return as if it was a free email domain
  if (!emailDomain) return true;

  // Gmail and Outlook are one of the most common email domains so we don't need to check the domains list
  if (emailDomain === "gmail.com" || emailDomain === "outlook.com") return true;

  // Check if email domain is in the watchlist
  const watchlistRepository = new WatchlistRepository();
  return !!(await watchlistRepository.getFreeEmailDomainInWatchlist(emailDomain));
};