Microsoft is sending out emails to Azure subscribers today to notify them that Guest operating systems based on Windows Server 2008 are being retired. Microsoft will be giving customers the chance to migrate to a supported guest OS until September 2, 2014 and will then simply shutdown the 1.x family of guides OS's on that date and remove it from the Azure portal.

For full information, visit the Azure Guest OS Family 1 Retirement Information page, though the email announcement today is just another step in the process for shutting down the old guest OS version. Microsoft has provided leading content for a few months already, so customers should already know about the expiration.

Here's the official email: