Replyblogs: Do you need a walled garden to protect against spam?

marcovhv followed up my earlier suggestion with:

Yes. And therefore without the associated spam that made trackbacks fail miserably.

There are plenty of blogs out there on the WWW happily accepting comments without requiring that users live in a walled garden. Many of them use services like Akismet to block spam and it seems to work rather effectively. Why should trackbacks be a significantly different problem to regular comment spam?

I have trackbacks enabled on a blog I run using WordPress, and I don’t see any trackback spam. I also successfully post trackbacks on a number of blogs that I’ve written responses to. Surely it can’t be that much of a problem?

At this point, your author pops over to another browser tab to do some poking.

The lack of spam I see is explained — Akismet deals with that too.