I've noticed this in the 1.6.2 release notes. While not DKIM, it might help.
- Mail Quota for App Engine apps that have signed up for billing will only be increased after the first payment for the app is processed. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appengine@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
