function checkEmail(emailStr) {

	if (emailStr.length == 0) {
		return true;
	}

	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) ||
	(domArr[domArr.length-1].length > 3)) {
		return false;
	}

	if (len < 2) {
		return false;
	}
	return true;
}