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

Question

I want to send email using SMTP client uiing microsft.net with C# as programming language. But for the emails sent through SMTP client, can we add security features like "no forwarding" or "no copying" etc. I dont want recipients of the email to forward or copy the content of the email.

Answer 1

Lotus Notes (the mail client) looks at the "Sensitivity" header. Using System.Net.Mail, you can accomplish the same thing (ONLY if your users are all using Lotus Notes) by using the following:

mail.Headers.Add("Sensitivity", "Company-Confidential");

The Lotus Notes email client will disallow forwarding or copying, just as if you had used the Lotus Notes COM object.

Answer 2

Simple answer: no. You can't keep people from copying something that's reached their machine.

If you explain why you're trying to do this, maybe we could offer a practical alternative. For example, if you don't want your text to be read by a robot, it could be in an image. If you have a binary attachment you don't want distributed, there are various kinds of DRM that may work for you.

Edit

A proprietary client (such as Lotus Notes) can disable itself based on metadata that comes with the message; but that's still voluntary. You could probably write a non-compliant Notes client that ignores such restrictions.

Edit

It didn't occur to me that your users might all be using the Notes client. In that case, @Peter J's solution may be what you need.

Answer 3

Email them a link that requires them to login. Or, if all of your users are on the same Exchange server, you could implement Exchange's Information Rights management. Otherwise you could look into sending encrypted emails. But there is still nothing to prevent them from copying it, be it by taking a screenshot, a picture with a camera, etc.