function isEmail(address) {
	var isValid = false;
	// basic checks (relying on lazy evaluation for correct behaviour!)
	// not empty
	// at least 7 characters (x@yy.zz)
	// has @
	// has only 1 @
	// has at least one . (domain.ext)
	isValid = (address!=null) 
	       && (address.length >= 7) 
	       && (address.indexOf('@')!=-1) 
	       && (address.indexOf('@') == address.lastIndexOf('@'))
	       && (address.indexOf('.')!=-1)
	;
	
	if (isValid) {
		var parts = address.split('@');
		var name  = parts[0].split('.');
		var host  = parts[1].split('.');
		var regName  = new RegExp("^([!#$%&'*+-/0-9=?A-Z^_a-z{}~]+)$"); // at least length 1
		var regLabel = new RegExp("^(^[-0-9A-Za-z][-0-9A-Za-z]+)$"); // at least length 2
		var regExt   = new RegExp("^([A-Za-z]{2,63})$"); // at least length 2
		var i;
		for (i=0; i < name.length; i++) {
			isValid = isValid && (name[i].search(regName) != -1);
		}
		for (i=0; i < host.length-1; i++) {
			isValid = isValid && (host[i].search(regLabel) != -1) && (host[i].length <= 63);
		}
		isValid = isValid && (host[host.length-1].search(regExt) != -1);
	}
	return isValid;
}