def persons_contacted(self):
        """ Return all contacted persons"""

        dace_catalog = find_catalog('dace')
        novaideo_catalog = find_catalog('novaideo')
        identifier_index = novaideo_catalog['identifier']
        object_provides_index = dace_catalog['object_provides']
        result = []
        for email in self._email_persons_contacted:
            query = object_provides_index.any([IPerson.__identifier__]) &\
                    identifier_index.any([email])
            users = list(query.execute().all())
            user = users[0] if users else None
            if user is not None:
                result.append(user)
            else:
                result.append(email.split('@')[0].split('+')[0])

        return set(result)