PostJoint is the second guest blogging network that’s been knowingly penalized by Google.

We reported the penalty news Friday on our sister site, Search Engine Land, and PostJoint itself confirmed the penalty on its own blog yesterday.

PostJoint currently isn’t ranking on Google for its own name, a sure sign of a penalty and the same thing that initially happened to MyBlogGuest when it was penalized last month.

Much like that case, Google’s official warning to PostJoint mentions “unnatural inbound links” — part of the long-running confusing messaging that Google delivers via Webmaster Central. PostJoint also mentions that some of its users are seeing “unnatural outbound links” warnings in their webmaster account.

It also appears that a small number of our registered sites have been penalised with an “unnatural outbound links” penalty and have lost their PR. We think the action is most likely down to an overall discernible pattern of unnatural linking activity and that using PostJoint has contributed to this in some way (too much of anything can be bad for your health).

Our News Editor, Barry Schwartz, noticed that PostJoint’s blog post originally claimed that “only 16% of our sites have been hit,” and claimed that the low number “shows that Google can’t in fact trace all of the sites using PostJoint.” That stat (and the swipe at Google) has been edited out of their post.

In any case, PostJoint says the Google penalty isn’t the end of their company:

We will continue with the same values and focus on building relationships. Guest blogging will remain as a viable content marketing strategy even though its under attack from Google. Marketers will still want to reach their target audiences on blogs, and bloggers will still want to monetize their sites and offer a fresh voice to their readers.