I need to setup an Outlook system to send encrypted email attachments to a Thunderbird email client. I don't need to encrypt email the other direction. What steps do I need to follow to make this happen? I don't know the version of Outlook but believe it is at least 2003 or later. Thunderbird version is current.
Well, I don't have systems and software at hand to experiment and create precise instructions on your behalf, but I believe you could accomplish your need with GnuPG: GPG4Win on the Outlook end, and Enigmail on the Thunderbird end.