Yahoo CEO Marissa Mayer has issued an apology to users of the company’s Mail service after an extended outage affected 1 percent of its users this week.

Mayer called the downtime, which began late Monday, “unacceptable.” A “particularly rare” hardware failure caused the issue. According to Mayer, service is back for “almost everyone,” but the full restoration process is still ongoing.

“While our overall uptime is well above 99.9%, even accounting for this incident, we really let you down this week,” she said. “We can, and we will, do better in the future.”

Mayer’s also wrote in the post that the week had been “frustrating” for users, a bit of an understatement considering that Flickr also had downtime this week and a number of small businesses website owners are upset about having their sites deactivated due to the conclusion of a partnership with AT&T/SBC

Yahoo’s issues come at an especially unfortunate time, as AllThingsD recently published an internal memo reportedly from the firm’s executives berating their colleagues for not switching from Microsoft Outlook to Yahoo Mail.

An Update on Yahoo Mail [Yahoo Tumblr]

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