function emailCheck (emailStr) {

    var checkTLD=1;

    var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;

    var emailPat=/^(.+)@(.+)$/;

    var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";

    var validChars="\[^\\s" + specialChars + "\]";

    var quotedUser="(\"[^\"]*\")";

    var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;

    var atom=validChars + '+';

    var word="(" + atom + "|" + quotedUser + ")";

    var userPat=new RegExp("^" + word + "(\\." + word + ")*$");

    var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");

    var matchArray=emailStr.match(emailPat);

    if (matchArray==null) {

    alert("Your e-mail address does not appear or is incorrect");

    return false;

    }

    var user=matchArray[1];

    var domain=matchArray[2];

    for (i=0; i<user.length; i++) {

    if (user.charCodeAt(i)>127) {

    alert("Your e-mail address contains nonvalued characters.");

    return false;

       }

    }

    for (i=0; i&lt;domain.length; i++) {

    if (domain.charCodeAt(i)&gt;127) {

    alert("The domain name contains nonvalued characters.");

    return false;

       }

    }

    if (user.match(userPat)==null) {

    alert("The e-mail address seems incorrect, please check it.");

    return false;

    }

    var IPArray=domain.match(ipDomainPat);

    if (IPArray!=null) {

    for (var i=1;i<=4;i++) {

    if (IPArray[i]>255) {

    alert("Destiny IP is not correct!");

    return false;

       }

    }

    return true;

    }

    var atomPat=new RegExp("^" + atom + "$");

    var domArr=domain.split(".");

    var len=domArr.length;

    for (i=0;i<len;i++) {

    if (domArr[i].search(atomPat)==-1) {

    alert("The e-mail address seems incorrect, please check it, including the incorrect use of signs of score, commas, or dots at the end of the address.");

    return false;

       }

    }

    if (checkTLD && domArr[domArr.length-1].length!=2 &&

    domArr[domArr.length-1].search(knownDomsPat)==-1) {

    alert("Your e-mail address must finish with a domain name or two letters " + "country.");

    return false;

    }

    if (len<2) {

    alert("Your e-mail address needs the host name  - check it.");

    return false;

    }

    return true;

    }