var username1 = "com";

var username2 = "puna";

var hostname1 = "ut";

var hostname2 = ".com";

var hostname3 = ".a";

var hostname4 = "u";

document.write("<a href=mailto:" + username1 + username2 + "@" + hostname1 + hostname2 + hostname3 + hostname4 + ">"+ "PaTroll" + "</a>");