function emailCheck(emailStr) {
	if (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;
}