Sell Hack responded to LinkedIn's cease-and-desist letter by disabling its controversial browser plug-in from all LinkedIn pages and also deleted all processed data.

LinkedIn is putting its foot down about revealing user's email address associated with the account, even without a direct connection on the social network. The popular social network for professional accounts sent a cease-and-desist letter to Sell Hack, free browser plug-in for LinkedIn users from hacking in to hack into any person's profile and fetch the personal email address. In response, the startup confirmed that their extension no longer works on LinkedIn pages and also that all publicly visible processed data was deleted.

Sell Hack browser extension works as if it actually breaks into LinkedIn's systems to get user information. In reality, according to the Sell Hack team, the free plug-in searches the internet for publicly available data and displays the possible email address associated with the account. The information is not accessed through any breach, bug or vulnerability of the site. But an extended access to a person's LinkedIn profile comes at a cost. The extension secretly watches users' online activity and collects the information of any direct connection a user visits, Yahoo Tech reports.

Even so, the two-month old company refuses to be titled as "sneaky" and "nefarious."

"We've been described as sneaky, nefarious, no good, not 'legitimate' amongst other references by some. We're not," Sell Hack team said in an official blog post, Tuesday. "We're dads from the midwest who like to build web and mobile products that people use."

The browser extension can be installed like any other plug-in for browsers, including Google Chrome, Safari or Mozilla FireFox. After installing it, a new "Hack In" button appears on every LinkedIn profile. The person's associated email address is revealed once the button is pressed on a particular profile page.

Threatened by the way how the system works, LinkedIn's legal team approached Sell Hack with a cease-and-desist letter for several violations. The social network also advised its members to uninstall the plug-in.

"We advise LinkedIn members to protect themselves and to use caution before downloading any third-party extension or app," LinkedIn Senior Manager of Corporate Communications Krista Canfield told Yahoo Tech. "Often times, as with the Sell Hack case, extensions can upload your private LinkedIn information without your explicit consent."

Sell Hack went down without any resistance, but seems to have come up even stronger. The browser extension witnessed more signups than in the first 60 days combined!  According to its blog, the startup is building a better product that does not conflict with LinkedIn's privacy terms.