var numberOfChars = 28; 

var isInvalid = new e_makeArray(numberOfChars); 
var InvalidChars = new e_makeArray(numberOfChars); 

function InvalidEmail(emailaddress) { 

var temp = emailaddress; 
temp = temp.toLowerCase(); 

InvalidChars[1] = "'"; 
InvalidChars[2] = "\""; 
InvalidChars[3] = "\\"; 
InvalidChars[4] = "/"; 
InvalidChars[5] = "`"; 
InvalidChars[6] = ","; 
InvalidChars[7] = ";"; 
InvalidChars[8] = ":"; 
InvalidChars[9] = "|"; 
InvalidChars[10] = "?"; 
InvalidChars[11] = "<"; 
InvalidChars[12] = ">"; 
InvalidChars[13] = "["; 
InvalidChars[14] = "]"; 
InvalidChars[15] = "{"; 
InvalidChars[16] = "}"; 
InvalidChars[17] = "("; 
InvalidChars[18] = ")"; 
InvalidChars[19] = "="; 
InvalidChars[20] = "+"; 
InvalidChars[21] = "!"; 
InvalidChars[22] = "#"; 
InvalidChars[23] = "$"; 
InvalidChars[24] = "%"; 
InvalidChars[25] = "^"; 
InvalidChars[26] = "&"; 
InvalidChars[27] = "*"; 
InvalidChars[28] = " "; 

var dotPosition = temp.indexOf("."); 
if (dotPosition < 0) { alert("Missing the dot in your email address."); return true; }

var atPosition = temp.indexOf("@"); 
if (atPosition < 0) { alert("Missing the @ sign in your email address."); return true; }

for (var j = 1; j <= numberOfChars; j++) { 
isInvalid[j] = temp.indexOf(InvalidChars[j]); 
} 


for (var j = 1; j <= numberOfChars; j++) { 
   if (isInvalid[j] != -1) { 
      alert("Invalid character in email: "+InvalidChars[j]); 
			return true;
      j = numberOfChars + 1;
	 } 
   else {} 
} 
   return false; 
} 

function e_makeArray(n) { 
   this.length = n 
   for (var i = 1; i<=n; i++) { 
       this[i] = new String(); 
   } 
   return this; 
}