Spam has Internet-clogging potential and Microsoft Corp. has been working on this threat to Hotmail accounts. Some MSN Hotmail e-mails are being referred to junk boxes since Microsoft's announcement in June 2005 that Hotmail messages need to comply with Microsoft's Sender ID e-mail verification program. MSN uses a Sender Policy Framework (SPF) to identify authorized outbound e-mail server, and Microsoft will no longer carry e-mail from servers whose policy framework has not been published. Not all users rejoice at this move. Trials of the MSN protocol have shown some messages were indeed referred to the junk box bearing the message, 'Sender could not be verified.' This is not, as some critics maintain, yet another autocratic move from the biggest kid on the block; most servers are SPF-compliant and over 1 million domains have published their SPF records. Microsoft defends its right to protect consumers and help businesses. This level of protection, maintain company executives, provides information about e-mails of dubious origins. Hotmail's new policy is certain attracting attention from small to midsize companies, though large-scale corporate response appears to be sluggish. To be fair, this is not exactly a new move; Yahoo! announced what it called DomainKeys for e-mail authentication in 2004 but chose to treat it more as a proposal than a requirement. Industry observers believe Yahoo! will scent which way the cyberspace winds are blowing and, if Hotmail's success is scented, Yahoo! will happily board the bandwagon.