Cannot send from multiple recipients with smtp module

On contact.pages.inc, the contact form sends the mail thus:
drupal_mail('contact', 'page_mail', $contact['recipients'], language_default(), $values, $from);

Then if the send myself a copy box is checked, it inverts the 'to' and the 'from'
drupal_mail('contact', 'page_autoreply', $from, $language, $values, $contact['recipients']);

Then, if there was more than one recipient, the smtp module objects when it does valid_email_address($from), and the user sees an error.