Is there a plugin to record querystring parameters for a page (for customer tracking)? [closed]

I am creating an information landing page that I intend to cold email out to a bunch of potential clients. I need to track customers that not only open the email (I know how to do that) but track which email recipients actually navigated to the landing page.

In a custom web application I would do this by sending them a link to the landing page that’s something like www.site.com/landing?rec=my@email.com, and upon seeing the querystring I would put that in the database.

Are there any WordPress plugins to do something like that?

WP is not really interested in what you add to the url string. But you could extract the url with native php functions and add your parts to the global wp_query; object using add_query_arg(). Then you can receive it via get_query_var() anywhere you need it.

You could also use a hook to do the adding-job:

function wpse42947_add_query_vars( $vars )
{
    $vars[] = "WHATEVER";
    return $vars ;
}
// hook add_query_vars function into query_vars
add_filter( 'query_vars', 'wpse42947_add_query_vars' );