Case of non existant email (legacy accounts)

users/forms.py

@@ -144,13 +144,16 @@ class UserCreationForm(FormRevMixin, forms.ModelForm):
         super(UserCreationForm, self).__init__(*args, prefix=prefix, **kwargs)
 
     def clean_email(self):
+        if self.cleaned_data.get("email"):
             if not OptionalUser.objects.first().local_email_domain in self.cleaned_data.get(
                 "email"
             ):
                 return self.cleaned_data.get("email").lower()
             else:
                 raise forms.ValidationError(
-                _("You can't use an internal address as your external address.")
+                    _("You can't use a {} address.").format(
+                        OptionalUser.objects.first().local_email_domain
+                    )
                 )
 
     class Meta:
@@ -349,6 +352,7 @@ class AdherentForm(FormRevMixin, FieldPermissionFormMixin, ModelForm):
     )
 
     def clean_email(self):
+        if self.cleaned_data.get("email"):
             if not OptionalUser.objects.first().local_email_domain in self.cleaned_data.get(
                 "email"
             ):
@@ -756,6 +760,7 @@ class EmailSettingsForm(FormRevMixin, FieldPermissionFormMixin, ModelForm):
             self.fields["local_email_enabled"].label = _("Use local emails")
 
     def clean_email(self):
+        if self.cleaned_data.get("email"):
             if not OptionalUser.objects.first().local_email_domain in self.cleaned_data.get(
                 "email"
             ):