A blackmailer demanded $1,500 to not point 20,000 XRumer forum profile backlinks at our site. Here is the email in full, Google's response to the campaign, and a 2016 follow-up DDoS extortion attempt.

Over the years we have been the target of several negative SEO campaigns. This morning's email tops all of them. The sender does not beat around the bush and states it plainly: "this is an extortion email".
Subject: I Want To Buy. Please Guide Me.
Hello,
Read this email very carefully.
This is an extortion email.
We will do NEGATIVE SEO to your website by giving it 20,000 XRumer forum profile backlinks (permanent & mostly dofollow) pointing directly to your website and hence your website will get penalised & knocked off the Google's Search Engine Result Pages (SERP) forever, if you do not pay us $1,500.00 (payable by Western Union).
This is no false claim or a hoax, download the following Notepad file containing 20,000 XRumer forum profile backlinks pointing to http://www.negativeseo.cn.pn/ (this is our website and go and see on this website, you will find our email address issmt1@yahoo.com from which this email right now is being sent to you):
http://www.mediafire.com/download/eizjwnpq2rsrncu/20000-XRumer-Forum-Profile-Backlinks-Dofollow.txt
Just reply to this email to let us know if you will pay just $1,500.00 or not for us to refrain or not from ruining your precious website & business permanently. Also if you ignore this email and do not reply to this email within the next 24-48 hours, then we will go ahead and build 20,000 XRumer forum profile backlinks pointing directly to your website.
We are awaiting your wise decision.
RS
I backed up the list of URLs in case they took it down. If these people attack you, enrich your disavow file with it.
The Fresh Link Finder report is clean so far, so no attack has landed yet:

This was most likely a blanket email sent to a large number of businesses, but we will keep an eye on it.
Together with many other webmasters, we took proactive steps and encouraged Google to introduce a mechanism for dealing with malicious links. Google's original position on negative SEO shifted from "cannot harm" to "may harm", and they ended up building the link disavow tool. Let us hope that is enough.
Barry Schwartz's contact at Google commented on the situation:
We forwarded these negative SEO extortion emails to Google and Google responded that they have "investigated" the claims. They added that it is "unclear how credible this threat really is." Google told us their "algorithms are designed to prevent these kinds of activities from causing problems for webmasters." Source: Search Engine Land
Several of our readers and friends received the same email. Steve Webb from Web Gnomes was one of them. He also showed that the threat is credible, despite Google's doubts:
"I have sent emails to 60+ webmasters about this negative SEO and some of them has responded positively and some of them have responded negatively. You are the only one who has responded anonymously. Those webmasters, who are responding negatively or not responding at all, will have their websites done with the negative SEO, including you, if you do not pay up." Source: Web Gnomes
Steve also published the attacker's (or their proxy's) name, address and phone number.
A short update on a later DDoS attack, where the attacker asked for $900. The best part is the "BR" sign-off.
