How do I prevent MS Exchange users from forwarding or copying a message sent via System.Net.Mail?

Question

如何防止MS Exchange用户转发或复制通过System.Net.Mail发送的邮件？

Answer 1

除非您编写一个Outlook插件，否则即使您不能这样做，确定的用户也始终能够以一种或另一种方式来实现。

Answer 2

You can't. If the email message was sent via Exchange rather than SMTP, you might be able to...with a server-side Exchange plugin/extension. But if the mail is sent via SMTP and is outside the Exchange server, you're SOL. The mail message is nothing more than a simple text file. Which see RFC 5322: Internet Message Format .

Further SMTP itself is a store-and-forward protocol. Every mail server involved in moving the message from sender to recipients gets a copy of the message and can keep it around.