When I run the test email, I get:
AmazonSES Error: HTTP/1.1 200 OK x-amzn-RequestId:263df2de-f794-11e1-a82b-a96b1a457f49 Content-Type: text/xml Content-Length: 338 Date: Wed, 05 Sep 2012 19:59:06 GMT 000001399803c1dc-ed40bd85-dcbc-47b1-bb0e-45abcb6f44fb-000000 263df2de-f794-11e1-a82b-a96b1a457f49
The test email however does get sent.
http://wordpress.org/extend/plugins/amazon-ses-and-dkim-mailer/