Test: Link Prefetch
In the <body> of the HTML part, place a tag as follows: <link rel="prefetch" href="http://TRACKING_URL/"> User agents which support the link prefetch mechanism will fetch the tracking url when they come across this html tag
In the <body> of the HTML part, place a tag as follows: <link rel="prefetch" href="http://TRACKING_URL/"> User agents which support the link prefetch mechanism will fetch the tracking url when they come across this html tag