Swiss-based ProtonMail is suffering from an ‘extremely powerful’ distributed denial-of-service attack that has knocked it offline and stopped users from accessing their inboxes. The firm says that it is working hard to restore normal operations, but at the time of writing the site remains offline. The attack began on Tuesday November 3rd, firstly flooding its IP addresses and then targeting the Swiss data centre where it houses its servers. According to the firm, the websites of several other tech companies and even some banks were also disrupted as a result of the internet attack.”]