Edit: Well, whichever way it's supposed to be, it should be consistent within one FAQ. :)
FAQ Question #113
» How does my LiveJournal e-mail address work?
When you have a Paid Account, people can send mail to your @livejournal.com e-mail address, which is in the form of email@example.com, replacing "exampleusername" with your username.
The @livejournal.com e-mail address is not an actual e-mail service from which you can send email. It is a forwarding service only, also known as an e-mail alias. Any mail sent to your firstname.lastname@example.org address will be forwarded to whatever e-mail address you have listed on your Edit Personal Information page (http://www.livejournal.com/editinfo.bml). There is no additional mailbox to check, no POP3 server to connect to, and no extra hassle of setting up another e-mail account.
As an added security measure, you can select the level of visibility of your e-mail addresses, as seen on your User Info page (http://www.livejournal.com/userinfo.bml). On the Edit Personal Information page, look for the option labelled "Show your contact information on your LiveJournal?", and select your desired privacy settings.
You can completely disable your @livejournal e-mail address by logging in (http://www.livejournal.com/login.bml), going to the Admin Console (http://www.livejournal.com/admin/console/), and executing the following command:
set no_mail_alias 1
You can re-enable your @livejournal e-mail alias by executing the following command:
set no_mail_alias 0