Microsoft has warned its Office 2003 users that it will begin pushing the software's Service Pack 3 via Microsoft Update next month.

The notice followed a dustup earlier this month over new security settings in Office 2003 SP3 that blocked access to a swath of older file formats. After users complained on the company's support forums, and a software rival asked why its files were barred, Microsoft apologised and posted work-arounds to make it easier for users to unblock the formats.

However, Microsoft has now announced that it would add Office 2003 SP3 to its Microsoft Update listings beginning 27 February. Microsoft Update, a companion service to Windows Update, downloads patches and other fixes for the operating system as well as a number of the company's applications, notably Office.

"Those customers who have not already installed SP3 and that have chosen to receive updates automatically will start to receive the service pack as early as February 27," said a Microsoft spokeswoman. "[But] the distribution through [Microsoft Update] is a gradual process and so not every customer will see the service pack on February 27."

Microsoft Update and Windows Update take their instructions from the client PC's Automatic Updates settings; those let users specify whether updates will be automatically downloaded and installed, downloaded but not installed, or not downloaded.

Users who do not wish to automatically upgrade their copies of Office 2003 must set Automatic Updates to the second or third option above.

Microsoft's Office and Update teams said that the warning is in keeping with a policy that debuted with Office 2007 SP1, when the company promised that it would give users a 30-day warning before turning on an automatic service-pack update. In December, Reed Shaffner, worldwide product manager for Office, promised that Microsoft would not use Microsoft Update to deliver Office 2007's SP1 for at least three months, perhaps longer.

"This policy seems to have worked really well with SP3 because it gave the market plenty of time to evaluate the service pack, gave us time to address concerns, and now we can push it to the hundreds of millions of users who depend on us to keep them secure," said the two teams in a combined posting to a company blog.

Office 2003 SP3 was announced last September and has been available for downloading from the company's website since then.