Status Code 403: SignatureDoesNotMatch when I am using Amazon SES

SMTP Credentials are not valid for use with SES API (AWS Java SDK). SMTP credential are in fact different to the ones manually created for IAM users, even that this different is not visible anywhere on AWS Console. Take a look here to see differences: http://docs.aws.amazon.com/ses/latest/DeveloperGuide/using-credentials.html

You don't actually need to create Global Access credentials (which could be a security leak), but you should create a new IAM user with the following security policy, and create new credentials for that user.

{
"Version": "2012-10-17",
"Statement":[{
   "Effect":"Allow",
   "Action":["ses:SendEmail", "ses:SendRawEmail"],
   "Resource":"*"
   }
]
}

PS: Probably, you could just add new credentials to the SMTP IAM user already created for SES, but I haven't yet tested this.

The keys to be provided to send Emails are not "SMTP Credentials" . The keys are instead Global access key which can be retrieved http://docs.amazonwebservices.com/ses/latest/GettingStartedGuide/GetAccessIDs.html.