The PGP support in PBM is currently using Bouncy Castle PGP 1.6.x and is compliant with inline PGP messaging. If you have a PGP keyring that was created by anything other than a version of PGP compatible with this, you will have to download a newer PGP version and create a new key pair (public/secret keys).
If you have a keyring that was generated by the latest Open PGP tools, you can skip this step, otherwise first download a copy of GnuPG or some other PGP key tool for your platform. OS X users can also check out GPG Suite. After installing the tool, create a keyring following the instructions defined by the tool you are using. It'll ask you to create a PGP ID, use your name followed by your email address in brackets: Joe Polar <jpolar@example.com>.
Now you have to tell PBM where to find your keyring. In PBM go to the Settings dialog and select the PGP page. Enter the paths to each keyring, the public keyring and the secret keyring. You must enter the full path to those files. After you have filled in the keyrings, use the Find ID button and select your ID from the list. If you would like your passphrase stored in the settings, enter it here and use the Test Passphrase button to make sure you typed it correctly. If you choose not to enter it here, you will be prompted for it when Polarbar attempts the first retrieval and if you are worried about leaving your passphrase in memory, you can clear it by selecting Tools->PGP->Clear PGP Passphrase
To encrypt an email, bring up the Compose dialog. Enter the name(s) of users which you currently have public keys for. You can use the Tools->View Public PGP IDs to view a list of currently known IDs that are part of your PGP public key collection. You can choose to sign or encrypt or both to the message you wish to send. Based on your sign/encrypt settings, when you send the email the actions will be applied to the outgoing message.
To sign an email, bring up the Persona dialog and check the "PGP Sign Email" checkbox at the bottom. The PGP signing can take a few seconds so don't worry if you press send and the compose dialog doesn't disappear right away.
To encrypt an email, bring up the Persona dialog and check the "PGP Encrypt Email" checkbox at the bottom. The PGP encryption can take a few seconds so don't worry if you press send and the compose dialog doesn't disappear right away.
Once the passphrase has been entered, any email received will be automatically verified. If the message is PGP signed you will see the text of the message begin with -----BEGIN PGP SIGNED MESSAGE-----. If the user's public key is on your keyring and the message was verified, a green padlock will appear in the subject line. If it fails verification the padlock will have a red X through it. If the message was signed but the user is not on your keyring, no PGP icons will appear in the subject.
To decrypt an email, simply RMB on the message and select PGP->Decrypt PGP message. The existing text in the window will disappear and the decrypted text will be shown. If you change to another message and then change back, you will see the encrypted text and you will need to decrypt it again.
If someone has sent you their ascii keyblock, you can add them to your keyring by pressing RMB in the message window and selecting PGP->Add PGP keyblock to public keyring. PBM can also search the PGP Key Servers if you select RMB->PGP->Get FROM addr public key from keyserver and add it After you add the public key for someone, you can manually verify their email by RMB->PGP->Verify PGP signature in message.
To see who is on your public keyring go to Tools->PGP->View Public PGP IDs
To distribute your public key to others you can make sure the Autocrypt header is enabled in Options->PGP or publish your key to some public server using the key tool you used to generate your public/secret keys.