//Validar mail
function Validate_String(string, return_invalid_chars)
 {
 valid_chars = '1234567890-_.^~abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
 invalid_chars = '';
 
 if(string == null || string == '')
    return(true);
 
 //For every character on the string.   
 for(index = 0; index < string.length; index++)
    {
    var ch = string.substr(index, 1);                        
    
    //Is it a valid character?
    if(valid_chars.indexOf(ch) == -1)
      {
      //If not, is it already on the list of invalid characters?
      if(invalid_chars.indexOf(ch) == -1)
        {
        //If it's not, add it.
        if(invalid_chars == '')
           invalid_chars += ch;
        else
           invalid_chars += ', ' + ch;
        }
      }
    }                     
    
 //If the string does not contain invalid characters, the function will return true.
 //If it does, it will either return false or a list of the invalid characters used
 //in the string, depending on the value of the second parameter.
 if(return_invalid_chars == true && invalid_chars != '')
   {
   last_comma = invalid_chars.lastIndexOf(',');
   
   if(last_comma != -1)
      invalid_chars = invalid_chars.substr(0, $last_comma) + 
      ' and ' + invalid_chars.substr(last_comma + 1, invalid_chars.length);
              
   return(invalid_chars);
   }
 else
   return(invalid_chars == ''); 
 }


function validate_email_address(email_address)
 {
 //Assumes that valid email addresses consist of user_name@domain.tld
 at = email_address.indexOf('@');
 dot = email_address.indexOf('.');
 
 if(at == -1 || 
    dot == -1 || 
    dot <= at + 1 ||
    dot == 0 || 
    dot == email_address.length - 1)
    return(false);
    
 user_name = email_address.substr(0, at);
 domain_name = email_address.substr(at + 1, email_address.length);                  
 
 if(Validate_String(user_name) === false || 
    Validate_String(domain_name) === false)
    return(false);                     
 
 return(true);
 }
 
function es_mail(ob)
{
	if(!validate_email_address(ob.value))
	{
		ob.style.border = "1px red solid";
		$('mail_valido').innerHTML = '<img src="../media/imagenes/icons/cancel.png" alt=""/> El mail no es v&aacute;lido.';
	}
	else
	{
		ob.style.border = "1px green solid";
		$('mail_valido').innerHTML = '<img src="../media/imagenes/icons/accept.png" alt=""/> El mail es v&aacute;lido.';
	}
}