撤回outlook邮件：双击已经发送的邮件->actions->recall this message.

搞定，

成功撤回的前提是对方还没有阅读发送的邮件，如果对方还没有阅读，显示如下：

Your message

      To:   Li, An       Subject:  ?????AT??      Sent: 2018/6/25 14:22

was recalled successfully on 2018/6/25 14:22.

如果对方已经阅读，你会收到如下系统邮件：

Your message

      To:   Li, An       Subject:  ?????AT??      Sent: 2018/6/25 14:22

cannot be recalled on 2018/6/25 14:22.