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("Email address seems incorrect (check @ and .'s)");
        return false;
    }
    var user=matchArray[1];
    var domain=matchArray[2];
    for (i=0; i<user.length; i++) 
    {
        if (user.charCodeAt(i)>127) 
        {
            alert("Ths username contains invalid characters.");
            return false;
         }
    }
    for (i=0; i<domain.length; i++) 
    {
        if (domain.charCodeAt(i)>127) 
        {
            alert("Ths domain name contains invalid characters.");
            return false;
        }
    }
    if (user.match(userPat)==null) 
    {
          alert("The username doesn't seem to be valid.");
          return false;
    }


    var IPArray=domain.match(ipDomainPat);
    if (IPArray!=null) 
    {
        for (var i=1;i<=4;i++) 
        {
            if (IPArray[i]>255) 
            {
                alert("Destination IP address is invalid!");
                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 domain name does not seem to be valid.");
            return false;
               
        }
    }
    if (checkTLD && domArr[domArr.length-1].length!=2 &&
    domArr[domArr.length-1].search(knownDomsPat)==-1) 
    {
          alert("The address must end in a well-known domain or two letter " + "country.");
          return false;
    }
    if (len<2) 
    {
        alert("This address is missing a hostname!");
        return false;
    }

    return true;
}