I'm not sure. It's hard to diagnose when it is working. Since it does seem to work with the Open Graph plugin enabled, I'm still unsure as to whether the Open Graph plugin is the cause of the issues in the first place. Without being able to see the problem, turn off the plugin and verify that was the cause, it's impossible for us to know we're the cause. There are many sites that use jReviews and JFBConnect without issue, but with all the different extension combinations out there, it's possible than any other extension is also the culprit. Beyond that, standard configuration problems, like the SMTP issue you ran into above, could be part of the problem as well.
Finally, the post to wall feature you're using is part of jReviews. If it's unreliable, and without being able to narrow it down to a specific issue with JFBConnect, I think they'd be the best to diagnose and resolve the issue.
Hope that helps explain our predicament. We'll gladly assist how we can, as we have in the past, but I'm not sure where to go from here for something that appears to be working for me.
Thanks,
Alex