A LinkBack is a mechanism for bloggers to obtain automatic notifications when other bloggers link to their posts. LinkBacks are an important pillar of the blogosphere because they allow blog posts to cross-reference each other. Over the last few years, spammers have consistently tried to abuse LinkBack mechanisms as they provide an automated way to inject spam into blogs. A recent study shows that a single blog may receive tens of thousands of spam LinkBack notifications per day. Therefore, there is a great need to develop defenses to protect the blogosphere from spammer abuses. To address this issue, we introduce TalkBack, a secure LinkBack mechanism. While previous methods attempt to detect LinkBack spam using content analysis, TalkBack uses distributed authentication and rate limiting to prevent spammers from posting LinkBack notifications.