function is_email (emailStr) {
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) {
	return false;
}

var user=matchArray[1];
var domain=matchArray[2];

if (user.match(userPat)==null) {
    return false;
}

var IPArray=domain.match(ipDomainPat);
if (IPArray!=null) {
	  for (var i=1;i<=4;i++) {
	    if (IPArray[i]>255) {
		    return false;
	    }
    }
    return true;
}

var domainArray=domain.match(domainPat);
if (domainArray==null) {
    return false;
}

var atomPat=new RegExp(atom,"g");
var domArr=domain.match(atomPat);
var len=domArr.length;
if (domArr[domArr.length-1].length<2) {
   return false;
}

if (len<2) {
   return false;
}

return true;
}