function emailCheck (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);
	var msg='Please enter a valid email address';
	if (matchArray==null) {
		//Email address seems incorrect (check @ and .'s)
		alert(msg);
		return false;
	}
	var user=matchArray[1];
	var domain=matchArray[2];
 
	if (user.match(userPat)==null) {
	    // user is not valid
	    alert(msg);
	    return false;
	}
 
	/* if the e-mail address is at an IP address (as opposed to a symbolic
	   host name) make sure the IP address is valid. */
	var IPArray=domain.match(ipDomainPat);
	if (IPArray!=null) {
	    // this is an IP address
		  for (var i=1;i<=4;i++) {
		    if (IPArray[i]>255) {alert(msg);
			return false;
		    }
	    }
	    return true;
	}
 
	// Domain is symbolic name
	var domainArray=domain.match(domainPat)
	if (domainArray==null) {
		//The domain name doesn't seem to be valid.
		alert(msg);
	    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) {
	   // the address must end in a two letter or three letter word.
	   alert(msg);
	   //The address must end in a three-letter domain, or two letter country.
	   return false;
	}
 
	// Make sure there's a host name preceding the domain.
	if (len<2) {
	   //This address is missing a hostname!
	   alert(msg);
	   return false;
	}
return true;
}