I asked Scott the same question on Twitter.
His response: "The Brightmail agreement was 80% went to them, 20% to us. IronPort A/S was 100% to us. Customers liked BM and we were unproven."
His response: "The Brightmail agreement was 80% went to them, 20% to us. IronPort A/S was 100% to us. Customers liked BM and we were unproven."