What is the best method for encrypting an excel file in 2003? We currently use 2007, but the client uses 2003. I read this article here: and it basically states that its not a good idea to use 2003. We need a way of encrypting files, but the client does not want to have to install a program on the other end. We use pgp internally, an in order to encrypt an excel file without the client having pgp, requires us to create an self extracting exe file, which they will not except. Any help here??