I managed to make the body of the email in Spanish but Feedburner adds text in English at subject:
Activate your Email Subscription to: XXXX
at the beginning of the email:
You received this message because someone requested an email subscription for XXXX to a FeedBurner feed. If you did not make this request, please ignore the rest of this message.
and end :
This message was sent to you by FeedBurner (feedburner.google.com) You received this message because someone requested a subscription to the feed, XXXX.com.
If you received this in error, please disregard. Do not reply directly to this email.
Any ideas how to get this in Spanish too?