In general, if I have validation that is slightly complex I just implement the validate method and write it in
Java. Be sure to call super.validate.
The validator framework actually calls get methods on your ActionForm, correct? Maybe you could add a getMailingFields method to your form that returns an empty string if any of the fields are empty and then create a validation rule on mailingFields.
If you are using Dynamic forms, then this may not apply.
- Brent