After I added the website in the Google Webmaster tool, I received a notification that the site had too many un-natural links and violates Google quality guidelines. Since it's a huge content rich forum, we found that too many websites were linking to it. Having little control over these websites, I didn't quite bother to contact all of them (long list) and sent a reconsideration request. (Although, the site enjoyed good traffic from Google). I got the same message from Google that the site still violated quality guidelines. Well, I didn't bother too much as my website enjoyed consistent traffic.
Suddenly, 3 days back (28th August), my website got badly penalized by Google and since then the traffic has plummeted by 50%.
Now I am looking into that long list of back links and trying to figure out on how to go about contacting all those websites that have linked to my website.
Any tips in this regard would be much appreciated. Thanks!!