-(BOOL)editEmail:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string;
{
    NSArray* forbiddenCharacters = [NSArray arrayWithObjects:@"!",@"^",@"~",@"&",@"=",@"#",@"[",@"]",@"-",@"+",@"'",@"{",@"*",@"/",@"|",nil];
    NSString* newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
    for(NSString* forbiddenString in forbiddenCharacters)
    {
        if([string isEqualToString:forbiddenString])
        {
            return NO;
        }

    }
    if([newString length] > 5)
    {
        return  NO;
    }

    NSCharacterSet* mySet = [NSCharacterSet characterSetWithCharactersInString:@"@"];
    NSArray* components = [string componentsSeparatedByCharactersInSet:mySet];
    if([components count] > 2)
    {
        return NO;
    }

    return [newString length]<15;

}