The Mail.app plug-in enables the sending of secure emails, ensuring confidentiality and privacy protection.
However, it's important to note the current limitations of GPGMail. For instance, it doesn't support PGP keys distribution as defined by RFC 3156, although you can still send/receive exported keys. Additionally, encryption and signing operations apply to the entire message and can't be interrupted. You can't pick and choose which parts of the message to encrypt either.
If you try to redirect a PGP-MIME signed message, you'll lose the signature, and there's no warning if only part of the message was signed. It's worth noting that encrypted messages are stored encrypted and aren't indexed by Mail/Spotlight. Finally, GPGMail can't verify/decrypt messages containing multiple parts that aren't in OpenPGP-MIME format, such as those created by PGP 7 or previous versions.
Overall, if you can work around these limitations, GPGMail is a solid choice for PGP authentication and encryption within the Mail app.
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