Microsoft’s webmail service Outlook reportedly suffered a significant outage last week after self-styled hacktivist group Anonymous Sudan claimed responsibility for a series of DDoS attack on the email service provider.

In a series of posts starting from June 5, Anonymous Sudan on its Telegram channel said that it will continue to attack Microsoft until the company pays a ransom of US$1 million.

“Microsoft, today we played football with your services. Let’s play a fun game. The fate of your services, which is used by hundreds of millions of people everyday, is under our dominion and choice,” the group said.

“You have failed to repel the attack which has continued for hours, so how about you pay US$1,000,000  and we teach your cyber-security experts how to repel the attack and we stop the attack from our end? US$1 million is peanuts for a company like you!”

Several frustrated Outlook.com users expressed frustration on social media as a temporary outage affecting the service hampered their productivity at work.

Sharing a generic reply to all users who tweeted, Microsoft said that it is experiencing a technical issue that caused these outages.

“We’ve identified that the impact has started again, and we’re applying further mitigation. Telemetry indicates a reduction in impact relative to earlier iterations due to previously applied mitigations. Further details about the workstreams are in the admin center via MO572252,” Microsoft tweeted.

“Our telemetry indicates that the service has remained largely stable; however, the incident is not fully resolved. We’re broadening our mitigation strategy and will continue to intervene immediately should we detect further reductions in the availability of our services.

“We continue to observe stable service health since we’ve applied our various preemptive mitigations and we will closely monitor the service should there be a recurrence,” the Redmond giant added.

Anonymous Sudan continued to publish several posts to brag about targeting Microsoft, mostly mocking the company.

“We stopped the attack, we will be satisfied with this amount 3 hours. In total, today, we have downed most of Microsoft services for 4.5 hours. Microsoft knows we are behind the attack, but they are hiding it because this is a big shame and embarrassment to a company this size to be humiliated this hard,” a post read.

The hacker group also claimed to have stolen the information of “more than 30 million customers” and has threatened the company to sell the allegedly stolen information. The group, however, said it stopped the attacks after two hours, threatening that it “will surprise them again with a new attack very soon.”