ureech,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
.mail{
display:none
}
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script>
$(function(){
var mail = $(".mails, .mail"), email = "text";
mail.on("click", function() {
mail.toggle().eq(1).text(email);
})
})
</script>
</head>
<body>
<span class="mails">Показать E-Mail</span>
<span class="mail"></span>
</body>
</html>