Microsoft said yesterday it had introduced a white list scheme to allow well-behaved email marketing firms to reach its customers without falling foul of its spam filters. Marketing firms who post a cash bond of up to $20,000 through IronPort's "Bonded Sender Programme" will get guarantees that their message will be delivered to the estimated 170 million regular users of Microsoft's Hotmail and MSN e-mail services, providing they follow a strict set of guidelines. Firms who flout the guidelines - standards that exceed those defined in the CAN-SPAM Act - risk losing their money. The approach rewards marketeers who agree to be held accountable for the messages they send. Microsoft has been working on the programme with IronPort for five months but the arrangement was only made public yesterday. Read more: The Register.