On first glance, the email arrives as the familiar "Subject: VIRUS-Warning email". But the solution inside the email was surprisingly not about an ongoing Internet virus, but about the HIV-Virus. With the surprise factor, we made it easy for users to forward this email to friends. Because it's always better to send a surprise to friends rather than a plain boring message.

The costs where zero. There is no click rate counting on private forwarded emails but the feedback received by the client was pretty amazing and showed that people loved the idea and used the forward function.