Updating an entry after an event action within onSaveEntry

Question

I have written a plugin that checks if an entry has been saved and sends the user an email from within an onSaveEntry event. This works fine. But I now need to also update this entry to flag that an email has been sent so that subsequent saves do not fire the event. I have tried adding the following but these lines do not work and cause an infinite loop.

$entry->setContentFromPost(['emailSent' => '1']);
craft()->entries->saveEntry($entry);

Is there a way to re-save the entry after the email has been sent so as just to update the emailSent field?

Full function:

public function onSaveEntry(Event $event)
{
    $entry = $event->params['entry'];
    if($entry->sectionId == '12345') {
        if($user = craft()->users->getUserById($entry->authorId)) {
            if($entry->enabled && !$user->admin && !$entry->emailSent) {

                // Send Approved Mail
                $email = new EmailModel();
                $email->fromEmail = 'me@mydomain.com';
                $email->toEmail = $user->email;
                $email->subject = 'Email Subject';
                $email->body    = '<p>Email Body</p>';
                craft()->email->sendEmail($email);

                $entry->setContentFromPost(['emailSent' => '1']);
                craft()->entries->saveEntry($entry);
            }
        }
    }
    return $event;
}

Answer 1

Use craft()->elements->saveElement the second time. It will work exactly the same but won't trigger the onSaveEntry event.