535 Authentication Credentials Invalid

...
  iamRoleStatements:
    # Allow the lambda function permission to create EINs, which is part of the
    # AWSLambdaVPCAccessExecutionRole
    - Effect: "Allow"
      Action:
        - "ec2:CreateNetworkInterface"
        - "ec2:DescribeNetworkInterfaces"
        - "ec2:DeleteNetworkInterface"
        - "ses:SendEmail"
        - "ses:SendRawEmail"
      Resource: "*"
    # end IAM role statements
   ...

MAILER_URL=smtp://email-smtp.us-east-1.amazonaws.com:587?encryption=tls&username=YOUR_SES_USERNAME&password=YOUR_SES_PASSWORD