Define validator `multiple_email_validator` that splits value by commas and calls `validate_email` validator for each element found. Then define MultipleEmailField with this default validator and augmented max_length. Then ... use it!
Using the `run_oldforms_validators` function, you can run oldforms validators in your newforms `clean_XXX` methods. Usage example: class PasswordForm(forms.Form): password = forms.CharField(widget=forms.PasswordInput()) def clean_password(self): validator_list = [ isStrongPassword, isValidLength, SomeValidators( num_required=3, validator_list=[hasLower, hasUpper, hasNumeric, hasSpecial], error_message="Password must contain at least 3 of: lowercase, uppercase, numeric, and/or special characters." ) ] run_oldforms_validators('password', self, validator_list) return self.clean_data['password'] Above, `isStrongPassword`, `isValidLength`, etc. are oldforms validators. If you are interested in seeing the implementation of `isStrongPassword`, please see my [Using CrackLib to require stronger passwords](http://gdub.wordpress.com/2006/08/26/using-cracklib-to-require-stronger-passwords/) blog post.
How to proceed to add a custom validator to a newforms field : you just need to create a new class derivated from forms.YourField with a custom clean method. Do not forget the line super(UserField, self).clean(value) ; in our case, it verifies the field attributes : min_length, max_length or required. More explications (in French) : [des validateurs personnalisés pour Django](http://www.aozeo.com/blog/67-django-newforms-validateurs-personnalises)
3 snippets posted so far.