Leave user email blank / null for compatilibity

users/models.py

@@ -205,6 +205,8 @@ class User(
         validators=[linux_user_validator],
     )
     email = models.EmailField(
+        blank=True,
+        null=True,
         help_text=_("External email address allowing us to contact you."),
     )
     local_email_redirect = models.BooleanField(