// JavaScript Document

function CheckEmail(emailstring) {	
	
	var AtSign = "@";
	var Dot = ".";
	var AtSignPOS = emailstring.indexOf(AtSign);
	var emailLength = emailstring.length;
	var DotPOS = emailstring.indexOf(Dot);
	
	if (emailstring.indexOf(AtSign) == -1){
	   alert("Please enter a valid email address.");
	   return false;
	}
	if (emailstring.indexOf(AtSign) == -1 || emailstring.indexOf(AtSign) == 0 || emailstring.indexOf(AtSign) +1 == emailLength){
	   alert("Please enter a valid email address.");
	   return false;
	}
	if (emailstring.indexOf(Dot) == -1 || emailstring.indexOf(Dot) == 0 || emailstring.indexOf(Dot) +1 == emailLength){
		alert("Please enter a valid email address.");
		return false;
	}
	if (emailstring.indexOf(AtSign,(AtSignPOS+1)) != -1){
		alert("Please enter a valid email address.");
		return false;
	}
	if (emailstring.substring(AtSignPOS-1,AtSignPOS) == Dot || emailstring.substring(AtSignPOS+1,AtSignPOS+2) == Dot){
		alert("Please enter a valid email address.");
		return false;
	}
	if (emailstring.indexOf(Dot,(AtSignPOS+2)) == -1){
		alert("Please enter a valid email address.");
		return false;
	}
	if (emailstring.indexOf(" ") != -1){
		alert("Please enter a valid email address.");
		return false;
	}
	
}