Add yourself as BCC to every e-mail leaving your WordPress website.

Paste this snippet inside your functions.php and change the example e-mail.
And voila! Every e-mail that leaves your website gets BCC’d to the email you specified.

add_filter( 'wp_mail','bcc_on_everything');
function bcc_on_everything($data){
$data['headers']="BCC: your@email.com \n";
return $data;
}