There is nothing Illegal about changing your User Agent, and you don't even need this Add-on to do it, you can always manually change your User Agent. Changing user Agents is used for many valid reasons (a poorly made website will only display properly if it thinks that you are using X browser, a web designer wants to test what his website does in different situations, a user likes how a website looks in Desktop mode but he users a mobile phone, etc.).

There is nothing this add-on does that is Illegal, and it's a totally legitimate add-on. I don't see why you think even if someone changed their User Agent to Google bot that will cause loss of Revenue.

The user agent string sent by the browser (or not sent by the browser) is information you cannot trust under any circumstances. In fact, many of the HTTP headers are untrustworthy, including HTTP_REFERER. Whether they are changed with an extension, or an external proxy, or other means, it is important to understand that you cannot rely on these strings to know what device or software is sending the request. (You also cannot trust bots to obey the robots.txt file, but that's another subject...)

Depending on the legal regime applicable to you and your network, your site's terms of use may or may not be enforceable. There may or may not be laws protecting your site against excessive use. Faking the user agent may or may not constitute unauthorized access. These are issues to address with your legal counsel.

I think the original purpose of the User Agent Switcher extension was as a tool for website developers to test differences in the page served to different browsers. It also was useful when some sites thought Firefox 1 was an older browser version than Netscape 6 (long, long ago), so that one could actually use the site. That seems legitimate to me.

I don't understand how the user agent string prevents you from "tracking back" who is accessing your site. In either case you get an IP address (which of course could be a proxy in either case), and you still can serve a link to Google Analytics or whatever other JavaScript-based tracking you employ.

If your site provides different content to different user agents, then you may be creating an incentive for users to lie to you. But why would you do that? I hope it's not so you can show real content in Google searches that then is blocked when users click through to your site. That is really annoying.

Finally, this is a support board. You may need to review the communication options on the Mozilla legal page as your next step: http://www.mozilla.org/en-US/about/legal.html.

Well , If Mozilla is not Keen in Solving this Issue then they will be Dealing with Big Players of Market most definately Google, Msn and Bing are few names to Keep in Mind. This is A Direct Violation of Google Property and all related Parties in this case. Its Matter of Split seconds that mozilla may find themselves in trouble due their lacking in admiting their responsibility to protect other concerned groups being abused due to a Addon , It may sound simple but its Addon Consequences are Severe to All Those affected.

As we said, this isn't Illegal, the add-on isn't doing anything wrong, and if you are doing questionable business practices on your website you should fix that. I'm going to lock this thread as this isn't a Firefox support Question.