trying to have different error through login with two hardcoded logins

if(empty($_POST['mail']) || empty($_POST['password']))
{
    header("Location: login1.php?error4");
}
else
{
    if(($_POST['mail'] == "peter@wijkmanska.se" && $_POST['password'] == "Webbserver") || ($_POST['mail'] == "hej@wijkmanska.se" && $_POST['password'] == "hej123"))
    {
        $login = true;
    }
    else
    {
        if(($_POST['mail'] != "peter@wijkmanska.se" && $_POST['password'] != "Webbserver") || ($_POST['mail'] != "hej@wijkmanska.se" && $_POST['password'] != "hej123"))
        {
            header("Location: login1.php?error1");
        }
        else if(($_POST['password'] != "Webbserver" && $_POST['mail'] == "peter@wijkmanska.se") || ($_POST['password'] != "hej123" && $_POST['mail'] == "hej@wijkmanska.se"))
        {
            header("Location: login1.php?error3");
        }
        else if(($_POST['mail'] != "peter@wijkmanska.se" && $_POST['password'] == "Webbserver") || ($_POST['mail'] != "hej@wijkmanska.se" && $_POST['password'] != "hej123"))
        {
            header("Location: login1.php?error2");
        }
        else{
            echo "wrong";
        }
    }
}

anyone knows what's wrong with it? it always does error1 unless I put nothing to log in then it gives me error 4 (empty fields gives error 4)