function emailCheck(emailStr) {
	emailStr = emailStr.toLowerCase();
	var checkTLD = 1;
	var knownDomsPat = /^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum|cat|jobs|mobi|travel)$/;
	var emailPat = /^(.+)@(.+)$/;
	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 +")*$");
	var matchArray = emailStr.match(emailPat);
	if (matchArray == null) { alert("Email address seems incorrect (check @ and .'s)"); return false; }
	var user = matchArray[1];
	var domain = matchArray[2];
	for (i = 0; i < user.length; i++) { if (user.charCodeAt(i) > 127) { alert("The username contains invalid characters."); return false; } }
	for (i = 0; i < domain.length; i++) { if (domain.charCodeAt(i) > 127) { alert("Ths domain name contains invalid characters."); return false; } }
	if (user.match(userPat) == null) { alert("The username doesn't seem to be valid."); return false; }
	var IPArray = domain.match(ipDomainPat);
	if (IPArray != null) { for (var i = 1; i <= 4; i++) { if (IPArray[i] > 255) { alert("Destination IP address is invalid!"); return false; } } return true; }
	var atomPat = new RegExp("^" + atom + "$");
	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;
	}