Someone tweeted to Matt that PostJoint was penalized.
In fact, if you check out Google for a search on their name, their web site no longer ranks on the first page.
Matt Cutts this morning confirmed it on Twitter saying “any link or guest blog network that claims to have “zero footprints” is waving a giant red flag.”
@techtada any link or guest blog network that claims to have "zero footprints" is waving a giant red flag.
— Matt Cutts (@mattcutts) April 18, 2014
Google recently also penalized My Blog Guest, another large guest blogging network.
I do not see a statement from PostJoint on this penalty yet.
PostJoint, like MyBlogGuest, did talk back to Matt Cutts early on about guest blogging being done. And then after MyBlogGuest was penalized, PostJoint explained how they are different. I guess not different enough?