So, sometimes when I have to give out an email address, I make a custom email address so that if it gets spammed, I can turn it off and I know who did it.
So, long ago, before I started this, I gave livejournal one of my regular email addresses - one that is no more or less defunct due to the amount of spam it gets.
A while later, I created lj at isnt.com which I eventually had to redirect to an auto-bounce as it started receiving regular spam.
At that time, I created lj2 at isnt.com which I have now started receiving spam to.
Keep in mind, I have never sent an email from these addresses and the only place I've given it is to my livejournal account. Now THAT email has begun to receive spam as well and will be shut off shortly.
My conclusion: LiveJournal has a leak which allows spammers to get their email addresses. Whether this is a mistake on LiveJournal's part or if they sell their email lists is unknown to me, but I will soon be receiving no emails via LJ.