In 2010 when I was applying for jobs I added a little tracker chunk of php to any page I sent to recruiters so I could get a notification if they actually clicked through. It worked pretty well. Primitive and intrusive but also pretty funny.

inc.tracker.php

<?php

	define('TRACK', false);

	function isSpider($HTTP_USER_AGENT) {
		$spiders = array(
			'Baiduspider',
			'msnbot',
			'youdao',
			'YandexBot',
			'YodaoBot',
			'KaloogaBot',
			'googlebot',
			'majestic12',
		);
		$is_spider = false;
		$haystack = strtolower($HTTP_USER_AGENT);
		foreach($spiders as $spider) {
			$needle = strtolower($spider);
			if (strpos($haystack, $needle) !== false) {
				$is_spider = true;
			}
		}
		return $is_spider;
	}
	
	$no_mail = array(
		'24.254.168.180', // ours
		'67.195.115.105', // yahoo bot
		'207.46.199.50', // msn bot
		'61.135.249.246', //youdao bot
		'207.46.199.32', // msn bot
		'68.183.146.41', // grandma's house
		'61.135.249.238', // youdao bot
		'123.125.66.85', // Baiduspider bot
		'68.8.173.141', // matt and margots
		'24.254.162.196', // mom and dads
		'24.254.162.43', // mom and dads
	);
	if (TRACK && !in_array($_SERVER['REMOTE_ADDR'], $no_mail) && !isSpider($_SERVER['HTTP_USER_AGENT'])):
		$headers = 'From: webmaster@artlung.com' . "\n" .
		    'Reply-To: webmaster@artlung.com' . "\n" .
		    'X-Mailer: PHP/' . phpversion() . "\n";
		$body = 'https://artlung.com/portfolio/2010/' . "\n\n". print_r($_SERVER, true);
		mail('joe@artlung.com', 'Email from https://artlung.com/portfolio/2010/ ' . $_SERVER['REMOTE_ADDR'], $body, $headers) or die("<!-- error -->");
		print "<!-- E -->";
	endif;