"You are being watched"というスパム。

I am working in a detective agency. I can’t say my name. I want to warn you that i’m going to monitor your telephone line. Do you want to know who is the payer? Wait for my next letter.

P.S. I know, you don’t believe me. But i think the tape of your yesterday’s telephone conversation will assure you that everything is real. The tape is in archive. Archive password is 123qwe