title: Get the user email after deletion in Django
body: <p>I was working with the settings.AUTH_USER_MODEL and I want the email of the user to remain( after the user deleted). The user is a foreign key in my model.
  Here is the code</p>
  <pre><code>class Text(models.Model):
      title = models.CharField(max_length=45)
      text = models.TextField()
      user= models.ForeignKey(
          settings.AUTH_USER_MODEL,
          on_delete=models.SET(??) )  # TODO : should change( remain email from the deleted user)
    
  </code></pre>
  <p>Thanks for your help.</p>