Dag,
Sorry for the delayed response to this. I just left a comment on your site and it posted immediately. The Javascript call that we use to send the email notification is being blocked, which is why you aren't getting the message. The Javascript error is that the following URL can't be called:
http://www.thailandstidende.com/index.php?option=com_jfbconnect&controller=social&task=commentCreate&href=http%253A%2F%2Fwww.thailandstidende.com%2Fcomponent%2Fk2%2Fitem%2F2183-dreamliner-til-qatar&commentID=165190566997026
If you go directly to that URL, you'll see that there is an Apache Forbidden message showing. I'm not sure what's preventing that URL from loading, but it's a valid URL. If you have a server or extension based firewall or other security product, look into it's log and see if it's blocking that page from loading.
I hope that helps get you started. Once we determine why that URL can't be called from our Javascript, we'll have our answer as to why you aren't getting the notification emails.
Thanks,
Alex