In an effort to help further secure and safeguard accounts from unauthorized access, Cryptic Studios has introduced a new security measure to Star Trek Online and Champions Online accounts dubbed Account Guard. The new feature will track computers that you authorize access to the game through and notify you when an unauthorized computer tries to access your account via email.
Additionally, when accessing your account billing information, a code will be sent to your registered email account, which will then need to be entered in order to access your account information.
For more details on the new feature, check out the Account Guard FAQ.
Source: Account Guard Announcement