This is the answer:
Thank you for contacting us. Your email address is not registered with LiveJournal. However, we've been receiving reports of emails with links to LiveJournal pages containing pornography or other unwanted content. I am very sorry that you are receiving those emails, but we are not sending them. LiveJournal only sends email from @livejournal.com addresses.
From our ongoing research, we believe that the persons sending these emails are harvesting addresses from any number of web locations, external to LiveJournal, and then simply spamming those addresses with links to LiveJournal pages they have created.
We can suspend the accounts these emails are linking to if you provide us the LiveJournal link included in the email. However, while we can take action to remove LiveJournal pages that contain inappropriate content, there is no action we can take to stop the actual sending of the emails themselves, as this activity is occurring outside of our control. You may wish to adjust your email spam filters to help prevent receiving spam from this source in the future. For example, if you do not have a LiveJournal account, you may wish to create a block for all email that contains the phrase 'livejournal.com'.