Envoy was a portable document format created by Tumbleweed software in the 1990s, later bought by Novell, and eventually abandoned when Adobe’s PDF became the dominant portable document format.
Viewer software for Envoy documents were available for 16-bit and 32-bit Windows and for the original Mac OS. The 32-bit Windows viewer runs in 64-bit Windows 10 (with compatibility set for Windows XP or other older versions), and other Windows viewers are available from the same page. These viewers, and ancient Macintosh versions, may also be found on this page. However, no viewer was ever made that runs on a modern Mac.
This Envoy Viewer app for current versions of macOS was made by wrapping the 32-bit Windows viewer in a Wineskin wrapper and modifying the wrapper so that it automatically opens .EVY files dropped on it. Because Wineskin wrappers cannot be notarized for macOS Gatekeeper, you will need to do one of the following before the application will open for the first time. First Cmd-click on the app; choose Open; if macOS tells you it can't verify the file, click Escape; then Cmd-click and choose Open again. If, however, macOS tells you that the app is damaged and should be sent to the Trash, then open a terminal and enter the following command:
xattr -rand type a space. (Do not forget the space!) Then drag the app into the terminal window and press Enter. The app should now run normally.
You should be able to print around twenty pages of an Envoy
document to a macOS printer at any one time, but memory
limitations may make it impossible to print large numbers of
pages. To print to a PDF file (with the same limitations), you
will need a PDF printer driver, either RWTS-PDFwriter
(free) or search for PDF Printer in the App Store (full version
must be paid for). To create a PDF from a large document, you will
need to create partial files and then combine them in macOS.
(There are complex workarounds that require a Windows system; feel
free to get in touch with me for details if you absolutely need
them.)