从收件箱中收集项目时，Exchange Web服务显示错误

Question

我收到错误

  

System.ArgumentException：集合为空。

尝试从我的收件箱中检索电子邮件时。我在Chrome中使用网络表单来托管此脚本。以下是使用Exchange Web Server从收件箱中检索电子邮件的代码块。

 try
    {
        //authenticate
        service = new ExchangeService(ExchangeVersion.Exchange2010_SP2);
        service.Credentials = new WebCredentials(_username, _password);
        service.TraceEnabled = true;
        service.TraceFlags = TraceFlags.All;
        service.AutodiscoverUrl(_username, RedirectionUrlValidationCallBack);

        //retrieve emails in blocks of 50
        int offset = 1;
        int pageSize = 50;
        bool moreEmails = true;

        emails.Clear();
        ItemView view = new ItemView(pageSize, offset, OffsetBasePoint.Beginning);
        view.PropertySet = PropertySet.IdOnly;

        while (moreEmails)
        {
            findResults = service.FindItems(WellKnownFolderName.Inbox, view);

            foreach (var item in findResults.Items)
            {
                emails.Add((EmailMessage)item);
            }

            moreEmails = findResults.MoreAvailable;

            if (moreEmails)
            {
                view.Offset += pageSize;
            }
        }

        properties = new PropertySet(BasePropertySet.FirstClassProperties);
        properties.RequestedBodyType = BodyType.Text;
        service.LoadPropertiesForItems(emails, properties);

        Response.Write(string.Format("<strong>I've found {0} emails </strong><br/>", emails.Count()));
    }
    catch (Exception ex)
    {
        Response.Write(ex.ToString());
    }

错误来自service.LoadPropertiesForItems(emails, properties); 行

我的收件箱中有电子邮件，因此我不确定为什么会发生此错误。任何帮助/方向表示赞赏！