So, Microsoft have decided to push ahead with their anti-spam technology, SenderID, introducing it as standard filtering into Hotmail. SenderID works with special DNS records that register which IP addresses are allowed to send email for a particular domain. This puts the onus on the email sender to ensure the IP address their email server is on has a matching record for domain in the From field of the email.

Will SenderID stop spam? Probably not, as it is relatively easy for a spammer to add the relevant DNS record. It should however help with phishing attacks, where it will be far more difficult to fool people into believing they are dealing with their bank and hand over sensitive data.

Currently, Hotmail just flags an email without SenderID with a yellow warning label, indicating verification was unsuccessful. But this is likely to progress to regarding such email outright as spam.

It's interesting that Microsoft are going ahead with their technology without industry-wide support - particularly Yahoo's DomainKeys stands in competition if a single standard is to be adopted. Clearly, they are trying to strong-arm the industry into accepting their standard, and the industry in general isn't happy about it. There are a number of technical problems with SenderID, including the handling of email forwards, which make it unpalatable. Currently, very few servers have the necessary records, and Hotmail is in no position to force organisations to publish them, especially on such a short timeline.

Got a Hotmail account? Time to move to Gmail.