title: MVC form block email domain
body: <p>I have a registration form on our site and in this is an email TextBoxFor and it works great until I got tasked with changing it to block users from using a specific email domain.</p>
  
  <p>So how can i get the form to block the user from using say "name@domainX.com" where DomainX.com is the bad domain but anything else passes and the account is registered.</p>
  
  <p>I have looked at using jQuery and got a popup box but that is not as neat as just forcing a error in the validation summary.  Looking at the data annotations on the Model Class and there is nothing there other than a RegEx I can think of.</p>
  
  <p>Suggestions please.</p>
  
  <p>Cliff.</p>