以前，我能够成功使用以下代码在Outlook中获取已读回执。但是最近我们公司搬到了Gsuite，现在可以通过Web访问GMAIL.COM来访问电子邮件了，我再也无法获得已读回执。如何从网络gmail邮箱获取已读回执？
msg = MIMEMultipart()
sender = <me>
subject = <others>
msg['From'] = sender
msg['Bcc'] = ','.join(address_book)
msg['Subject'] = subject
msg['Disposition-Notification-To'] = <me>