I think it's genuine, as those that have received them generally appear to have a Microsoft.net passport or have signed up for their newsletter. Though I will admit I binned mine as I got a security certificate warning when I accessed the link.
The alpha-numeric string that comes before the @ in the email address is your personal reference code in Microsoft's UK distribution database. The company is acting to protect your privacy by encrypting your address.
The fact that you've received the mail means that you must at some time agreed to receive email updates of one kind or another.
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