[HttpGet]
    public IHttpActionResult ListProperties(string domainName, string userName, string password)
    {
        try
        {
            using (DirectoryEntry dEntry = new DirectoryEntry("LDAP://" + domainName, userName, password))
            {
                DirectorySearcher dSearcher = new DirectorySearcher(dEntry)
                {
                    Filter = "(&(objectClass=user)(mail=" + userName + "))"
                };
                SearchResult sResult = dSearcher.FindOne();
                Dictionary<string, string> resultDictionary = new Dictionary<string, string>
                {
                    {"Name", GetProperty(sResult,"cn")},
                    {"Email", GetProperty(sResult,"mail")}
                };

                return Ok(resultDictionary.ToList());
            }
        }
        catch (Exception ex)
        {
            return BadRequest(ex.Message);
        }
    }


    private string GetProperty(SearchResult searchResult, string propertyName)
    {
        if (searchResult.Properties.Contains(propertyName))
        {
            return searchResult.Properties[propertyName][0].ToString();
        }
        return string.Empty;
    }

$(document).ready(function () {


    $.ajax({
        type: "GET",
        url: "../api/xxxxxxx/ListProperties",
        data: { domainName: "mydomain.xxx.xx", userName: "MyUsername", password: "MyPassword" },
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (data) { console.log(JSON.stringify(data)); },
        failure: function (data) { console.log(0); },
        error: function (data)   { console.log(1); }
    });
});

System.Runtime.InteropServices.COMException HResult=0x8007203A Message=The server is not operational.