Nobody's going to complain about their mailboxes being made 200 times larger, as Microsoft did at the end of last year, and Hotmail is known for its ruthlessness about spam, keeping its 24-hour deletion of junk and image blocks in place from when everyone's mailboxes were tiny. However now the company is pushing through its Sender ID technology, which means the spoofed headers used by spammers and virus writers will now bounce, and Hotmail will inform you when this has happened.

Legitimate marketing services are among the most vocal in their dissent at the product and of course, there's no confirmation of what happens when Hotmail, along with Yahoo, occasionally “forgets” an address which you specifically marked as not being spam.

ISPs and other companies with mail servers not wishing to be designated as spam sources need to publish a Sender Policy Framework (SPF) certificate to identify their mail servers. So far so good you might think except when you learn that some sections of the code behind Sender ID technology remained as part of Microsoft's patented intellectual property, meaning the Redmond giant would infest every server which posted a certificate, worldwide, and come to dominate the internet in an even more real way than it's perceived to do now.

The Internet Engineering Task Force (IETF) as a proposed standard refused to ratify the standard and of course this will not stop Microsoft introducing it anyway through the millions of hotmail accounts which exist. However, all of those users will need a method by which they can receive email sent from a server without a certificate and access “wanted spam” - for instance, a regular fan club email. This is Microsoft we're talking about though, so for a commonsense solution which will satisfy all sides, give it a few months - during which time server operators may decide to install Microsoft's software for a quiet life and, as Craig Spiezle Microsoft believes, “ultimately enhance their brand name.”