An anonymous reader writes: A few days ago, privacy-oriented webmail service ProtonMail was hit by a massive DDoS attack, which was accompanied by extortion. It turns out they're not the only ones. FastMail has warned that similar attacks could lead to service disruptions this week. They have refused extortion demands, and have been hit with a couple brief attacks already. This follows attacks over the last week on Runbox, Zoho, and Hushmail. Each service has been working with data centers and network providers to mitigate the attacks as well as possible, but they're still struggling with intermittent service disruptions.