With the assistance of GPG Suite, Apple Mail can support OpenPGP encryption for secure communications. Learn how to import your OpenPGP keypair into Apple Mail :

Before proceeding, ensure that you’ve installed GPG Suite and have configured your Mailfence account in Apple Mail. Additionally, confirm that you have exported your OpenPGP keypair from your Mailfence web-interface or any other source.

1. Open the GPG Keychain app, which is part of the GPG Suite you installed on your Mac.
2. In the GPG Keychain menu at the top, click on Import.
3. In the dialog box, navigate to the location where you have saved your exported OpenPGP keypair file. Select the key file and click on Open.
4. The GPG Keychain will then display the details of the key you’re importing. Verify that the displayed key corresponds to your Mailfence account email address and has the correct Key ID.
5. Ensure the option Treat this key as a Personal Key is checked. Click on Import.
6. Enter the passphrase and click OK.
7. Once imported, the key will appear in the list of keys in GPG Keychain. Confirm the Email address, Fingerprint, and other details of the imported keypair.

Now, when composing or reading emails in Apple Mail, you can use the GPG Mail component of GPG Suite (integrated with Apple Mail) to encrypt, decrypt, sign, or verify signatures using the imported keypair.

For additional details or to familiarize yourself with advanced features, consult the official GPG Suite documentation or user guide.