Might be an answer, or at least a starting point
Zix has a solution
google responds well to "Encrypt emails on a Mac"
P
Hey guys,
Have a quick question. My office uses both windows and mac based systems. We deal with highly sensitive information that we need to send to other departments securely. I'm looking for a piece of software that will encrypt a file on my mac, and can be opened with a password on another mac that does not have the software on it.

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