Update email only if the email doesn't exist in the database

Add a hidden form field named 'original_email' and set the value to the users email. This field will be used as reference to detect if the users has changed the email when saving.

In the form validation PHP code we only add the unique form validation if needed.

PHP Code:

// We do the unique check only if the email field to not match the original email
if ($this->input->post('email') != $this->input->post('original_email')) {
    $this->form_validation->set_rules('email', 'Email', 'trim|required|xss_clean|is_unique[users.email]'); 
}