Sendmail, which provides the commercial version of the open source sendmail e-mail software, will support any widely supported authentication scheme as a way to stymie increasing spamming and e-mail fraud. Schemes available include Domain Keys from Yahoo! and Microsoft Caller ID for Email. IT administrators should jump on the authentication bandwagon with alacrity, since e-mail authentication may be the best solution for stopping spam until SMTP can be replaced with a new mail specification, an event that will not occur anytime in the near future. Most antispam vendors suggest that spam will become about 70 percent of all e-mail by the end of 2004. IT managers should keep spam-filtering products installed, since authentication does not cover message content, but does verify that 'senders are who they say they are.' With authentication, content- and signature-based spam filters will work better to sort unwanted mail from wanted mail. When authentication of the sender is needed before the sender's message can access the recipient's, most spammers will have to find new employment. While such legislation as CAN-SPAM cannot be very effective in stopping SPAM, technology schemes such as authentication can be successful. New services are available that will increase the reliability of authentication, including Brightmail, which will use its global e-mail monitoring system to determine the amount of legitimate mail and spam emerging from e-mail sources.