Gmail无法识别电子邮件标记

Question

我尝试测试电子邮件标记的RSVP动作。我添加了带有标记的邮件内容并发送到自助邮件（不需要DKIM和SPF）。 但电子邮件标记无法识别。

标记是：

<p>
      Dear John, thanks for booking your Google I/O ticket with us.
    </p>
    <p itemscope itemtype="http://schema.org/EventReservation">
      BOOKING DETAILS<br/>
      Reservation number: <span itemprop="reservationNumber">IO12345</span><br/>
      Order for: <span itemprop="underName" itemscope itemtype="http://schema.org/Person">
        <span itemprop="name">John Smith</span>
      </span><br/>
      <div itemprop="reservationFor" itemscope itemtype="http://schema.org/Event">
        Event: <span itemprop="name">Google I/O 2017</span><br/>
        <time itemprop="startDate" datetime="2017-05-15T08:30:00-08:00">Start time: May 15th 2017 8:00am PST</time><br/>
        Venue: <span itemprop="location" itemscope itemtype="http://schema.org/Place">
          <span itemprop="name">Moscone Center</span>
          <span itemprop="address" itemscope itemtype="http://schema.org/PostalAddress">
            <span itemprop="streetAddress">800 Howard St.</span>,
            <span itemprop="addressLocality">San Francisco</span>,
            <span itemprop="addressRegion">CA</span>,
            <span itemprop="postalCode">94103</span>,
            <span itemprop="addressCountry">US</span>
          </span>
        </span>
      </div>
    </p>

我错过了什么吗？