resource "aws_sqs_queue_policy" "test" {
  ... 
  policy = <<POLICY
{
    "Version":"2012-10-17",
    "Statement":[
       {
          "Principal": "*",
+         "Effect": "Deny",
          "Action": "sqs:SendMessage",
          "Resource": "${aws_sqs_queue_policy.q.arn}"
       }
    ]
}
POLICY
}