I am trying to check that If email already exist in databse or not or not in database but my code throws error – Asp.net

This is the error I am getting in my console;

GET http://localhost:1089/api/Employee/EmailAlreadyExist?%[email protected]%22 404 (Not Found)

This my ajax code where I am sending the user email while creating a new user, and I want this method to let me know if the email already exist in database or not;

function CheckAvailability() {
    var email = $("#officialemail").val();
    $.ajax({
        type: "GET",
        url: 'http://localhost:1089/api/Employee/EmailAlreadyExist',
        dataType: 'json',
        contentType: "application/json",
        data: JSON.stringify(email),
        success: function (response) {
            var message = $("#message");
            if (response) {
                //Email available.
                message.css("color", "green");
                message.html("Email is available");
            }
            else {
                //Email not available.
                message.css("color", "red");
                message.html("Email is NOT available");
            }
        }
    });
}

function ClearMessage() {
    $("#message").html("");
};

and I am passing this entire function in another fucntion in which I am passing the email parameter in attempt of creating a new user along with all of the other parameters with their values;

$('.empOfficialDetails').click(function (ev) {
    ev.preventDefault();

    CheckAvailability()

    var data = new Object();
    data.UserName = $('#username').val();
    data.UPassword = $('#userpass').val();
    data.OfficialEmailAddress = $('#officialemail').val();
    data.Departments = $('#departments :selected').text();
    data.Designation = $('#designation :selected').text();
    data.RoleID = $('#role').val();
    data.Role = $('#role :selected').text();
    data.ReportToID = $('#reportToID').val();
    data.ReportTo = $('#reportTo :selected').text();
    data.JoiningDate = $('#joindate').val();
    data.IsAdmin = $('#isAdmin :selected').val() ? 1 : 0;
    data.IsActive = $('#isActive :selected').val() ? 1 : 0;
    data.IsPermanent = $('#isPermanent :selected').val() ? 1 : 0;
    data.DateofPermanancy = $('#permanantdate').val();
    data.HiredbyReference = $('#hiredbyRef :selected').val() ? 1 : 0;
    data.HiredbyReferenceName = $('#refePersonName').val();
    data.BasicSalary = $('#basicSalary').val();
    data.CurrentPicURL = $('.picture').val();

    if (data.UserName && data.UPassword && data.OfficialEmailAddress && data.Departments && data.Designation && data.Role && data.IsAdmin && data.IsPermanent) {
        $.ajax({
            url: 'http://localhost:1089/api/Employee/EmpOfficialDetails',
            type: "POST",
            dataType: 'json',
            contentType: "application/json",
            data: JSON.stringify(data),
            beforeSend: function () {
                $("#dvRoomsLoader").show();
            },
            complete: function () {
                $("#dvRoomsLoader").hide();
            },
            success: function (data) {
                var ID = parseInt(data);
                if (ID > 0) {
                    //var id = data;
                    $(".HiddenID").val(data);
                    //var id = $(".HiddenID").val();
                    $('#official').css('display', 'block');
                    $('#official').html("Employees Official details added successfully...!");
                    $('#official').fadeOut(25000);
                    $("#dvRoomsLoader").show();

                    $('.empOfficialDetails').html("Update &nbsp; <i class='fa fa-angle-right rotate-icon'></i>");
                }
                else {
                    $('#official').find("alert alert-success").addClass("alert alert-danger").remove("alert alert-success");
                }
            },
            error: function (ex) {
                alert("There was an error while submitting employee data");
                alert('Error' + ex.responseXML);
                alert('Error' + ex.responseText);
                alert('Error' + ex.responseJSON);
                alert('Error' + ex.readyState);
                alert('Error' + ex.statusText);
            }
        });
        
    }
    return false;

});

and in my controller I am using an inline query to check for similar email in my database;

[Route("api/Employee/EmailALreadyExist")]
    [HttpGet]
    public bool EmailAlreadyExist(string email)
    {
        string retval;
        var con = DB.getDatabaseConnection();
        Employee emp = new Employee();
        string query = "IF EXISTS (SELECT 1 FROM Employee WHERE OfficialEmailAddress = @OfficialEmailAddress)";
        SqlCommand com = new SqlCommand(query, con);
        com.Parameters.AddWithValue("@OfficialEmailAddress", email);

        email = emp.OfficialEmailAddress;
        SqlDataReader rdr = com.ExecuteReader();
        if (rdr.HasRows)
        {
            retval = "true";
        }
        else
        {
            retval = "false";
        }
        return Convert.ToBoolean(retval);
    }

all of the help I get is highly appreciated and sugesttions for making this code better are all warmly welcomed

thank you