GPGMail has been an invaluable tool for users of both GnuPG and Apple’s Mail application. For those unfamiliar with GnuPG (and its commercial equivalent, PGP), it uses a set of keys — one public, one secret — to encrypt and/or attach digital signatures to email.
Unfortunately, the marriage of GPG to Mail has been a bittersweet relationship. Apple doesn’t publish the internal API’s of Mail, and has not provided much of a plug-in architecture for it. Therefore, GPGMail had to be developed by using undocumented functions, which Apple had no obligation to maintain between major releases of macOS. Like all other major upgrades, Mac users upgrading to Snow Leopard were left to pick up the pieces. To add to the pain, the sole programmer behind this no longer has time to maintain the software.
While the software is getting a long-overdue rewrite from new hands, two enterprising users found a solution, which I’m reposting to spread the word.
- Download and install GPGMail and MacGPG.
- Find Mail in the
- From the File menu, choose Get Info.
- Check "Run in 32-bit mode". (64-bit support will have to wait until a new version of GPGMail is formally released.)
- Now, go to
~/Library/Mail/Bundles; right-click on
GPGMail.mailbundleand choose Show Package Contents.
- Add the following lines to
Info.plist, depending on which version of macOS that you’re running:
- Mac OS X 10.6
<key>SupportedPluginCompatibilityUUIDs</key> <array> <string>B3F3FC72-315D-4323-BE85-7AB76090224D</string> <string>225E0A48-2CDB-44A6-8D99-A9BB8AF6BA04</string> </array>
- Mac OS X 10.6.1
<key>SupportedPluginCompatibilityUUIDs</key> <array> <string>2610F061-32C6-4C6B-B90A-7A3102F9B9C8</string> <string>99BB3782-6C16-4C6F-B910-25ED1C1CB38B</string> </array>
- Mac OS X 10.6.2 (beta)
<key>SupportedPluginCompatibilityUUIDs</key> <array> <string>0CB5F2A0-A173-4809-86E3-9317261F1745</string> <string>2F0CF6F9-35BA-4812-9CB2-155C0FDB9B0F</string> </array>
- Save the file, and then open Mail.
Everything should be working fine now! Many thanks to detlefschmitt and pretemsteinmetz from the SourceForge.net forums for this solution. If you found this helpful, please thank the original posters, and then urge Apple to do any of the following:
- Provide native support for GnuPG in Mail, as they do S/MIME.
- Publish a Mail plugin API, to make development of GPGMail easier.
- Assign one or more members of the Mail development team to the GPGMail project.
- GPG Tools (for modern Macs)
- GPGMail (legacy)