And just FYI here is the thread I found with a similar problemhttps://forums.aws.amazon.com/thread.js ... adID=84033
From reviewing your detailed post, it would seem that SendBlaster, the program you're using to hand mail off to Amazon SES via SMTP, is inserting a header that is not allowed.
Specifically, SendBlaster appears to be inserting a "Received-SPF" header which contains the authentication results from the prior hop before SMTP handoff to Amazon SES. You can read more about the specific header here.
And here http://docs.amazonwebservices.com/ses/latest/DeveloperGuide/Headers.html
is the list of allowed headers Amazon SES supports.
Your use case is an interesting one, though, and I will be sure to add "Received-SPF" to the list we routinely review for making changes to the allowed header list.
In the meantime, I would suggest you contact SendBlaster and see if you can customize the headers that are transmitted during SMTP. I looked over their site and couldn't find anything myself, but I'm sure they'd be more than willing to help you.
Please let us know what you find out in case other folks are having the same issue.
Hope this helps,