Microsoft made that official late Friday in a post on the . "We have discovered several issues with the update and ... as of December 16, this Outlook 2007 update has been removed from Microsoft Update,"

According to Microsoft, the Tuesday update contained three flaws related to Secure Password Authentication (SPA), a Microsoft protocol used to authenticate mail clients like Outlook to a mail server; sluggish folder switching when Outlook wasn't configured to grab mail from an Exchange server; and a broken AutoArchive feature.

Microsoft urged users who had installed update during its three days of availability to remove it, and spelled out the necessary steps.

The company also issued a mea culpa.

"We apologize to our customers for not discovering these issues before releasing the update and for any inconvenience we have caused," the Outlook team wrote on its blog. "We failed to meet our own and our customers' expectation for quality with this update release. We are working to fix these issues and will post a release date for those fixes, and link to download them, as soon as that information is available."