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)");
			form.user_email.focus();
			return false;
	}
	var user=matchArray[1];
	var domain=matchArray[2];
	
	for (i=0; i<user.length; i++) {
			if (user.charCodeAt(i)>127) {
			alert("The e-mail username contains invalid characters.");
		return false;
	   }
	}
	for (i=0; i<domain.length; i++) {
	if (domain.charCodeAt(i)>127) {
				alert("The e-mail domain name contains invalid characters.");
				form.user_email.focus();
				return false;
	   }
	}
	
	if (user.match(userPat)==null) {
		alert("The username doesn't seem to be valid.");
		form.user_email.focus();
		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!");
			form.user_email.focus();
			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.");
				form.user_email.focus();
				return false;
	   }
	}
	
	if (checkTLD && domArr[domArr.length-1].length!=2 && 
	domArr[domArr.length-1].search(knownDomsPat)==-1) {
					alert("The e-mail address must end in a well-known domain or two letter " + "country.");
					form.user_email.focus();
					return false;
		}
	
	if (len<2) {
				alert("This e-mail address is missing a hostname!");
				form.user_email.focus();
				return false;
				}
	
	return true;
}