LinkedIn has issued a warning against a browser extension, Sell Hack, which hijacks the professional network to reveal its users’ personal email addresses.

Sell Hack is marketing its ‘Hack In’ button to salespeople as a way they can reach potential prospects, promising to “simplify prospecting ‘inside’ LinkedIn”.

The browser extension, which works on Chrome, Firefox and Safari, tells users it can “find hidden emails and more”.

According to The Next Web LinkedIn has sent a cease-and-desist letter to the company over what it described as “several violations”.

LinkedIn’s senior manager of corporate communications, Krista Canfield,  told The Next Web that LinkedIn members should uninstall Sell Hack “immediately” and request the platform delete their data.

Canfield said LinkedIn’s members should use caution and that Sell Hack could be uploading their private LinkedIn information without explicit consent.

Here is how Sell Hack describes the process: