Contextual newsletter: spammers have learned to track blogs?

I recapitulated yesterday in my LiveJournal the sensational post about the boorish appeal of the service for knocking out debts from Alfa Bank clients, and this afternoon I found two letters in a row on this topic in the Spam folder:



I looked through more than fifty letters that came before this - there is nothing about bank debts. On Habré, they already wrote about cases when spam unexpectedly coincided with the theme of recent searches in search engines - but I hear about blogs like this for the first time. How it works?