The IIM system works much the same way, except the public key is stored in the e-mail sender's outbound e-mail servers, while the private keys are stored in the DNS record. According to Cisco, storing the generic public key in the e-mail header instead of producing private key-based signatures each time a message is sent would take fewer computing resources from e-mail senders, compared to DomainKeys.
Yahoo! and Cisco currently are working to merge the two protocols to create an even more effective cryptographic solution. Although more effective, these solutions do require greater investment in e-mail delivery infrastructure, which, in part, has slowed their implementation by marketers. "When you're looking at an overtaxed IT department, it's easier for them to implement Sender ID then it is to implement domain keys," describes Robinson.
Word on the Street
Not surprisingly, marketers may be wary of investing in an infrastructure that is still a work in progress and are likely to wait for a more definitive solution to emerge. Tim Kiss, director of one-to-one marketing for Atlanta, Ga.-based catalog and online food marketer HoneyBaked Hams, offers a pragmatic perspective on the evolving state of authentication. HoneyBaked Hams began e-mailing its customers in 2000. Its first efforts were primarily discount-based. The marketer since has developed more actionable and personalized e-mail campaigns. Although its e-mail budget has grown to represent 10 percent to 11 percent of its total mail-order sales, the marketer has experienced a decline in response rates. Kiss attributes this in part to spam filters.
"We're starting to see that there is not going to be a one-fix technology that's going to separate us from the spammers," says Kiss. "But we've also started to see that if we don't start to do some of these things, we're going to be blocked out." The marketer therefore has implemented Sender ID and is SPF compliant.