A distributed denial of service (DDoS) attack means that the attackers are bombarding Hushmail's servers with junk Internet traffic, overloading the servers and preventing them from handling or responding to legitimate traffic, such as users' login attempts or the delivery of messages. A DDoS attack does not necessarily jeopardize the security of your data in and of itself, although sometimes attackers will conduct a DDoS attack as a diversion from another type of attack, e.g. one that actually does compromise your data. In this case, though, the group that has been attacking Hushmail and several other secure email providers is the Armada Collective, which has been trying to extort money from these companies in return for stopping the attacks, which costs those companies even more money than the attackers demand because the attacks disrupt their services and cause them to lose business.