★ Enterprise Edition — not included in the Community Edition. Compare editions

Encryption¶

PGP and S/MIME key management with on-demand encrypt/decrypt/sign/verify — plus what is already encrypted without you doing anything.

The Encryption service (container port 8084, published on host port 8093) is a working key-management and crypto API backed by GnuPG and MySQL. It is not wired into the mail flow — outbound mail is not automatically encrypted and inbound mail is not automatically decrypted. Use the API from your own application or workflows.

What is encrypted today, automatically¶

Layer	Mechanism	Status
Mail in transit	STARTTLS/TLS on Postfix (25/587/465) and Dovecot (IMAP/POP3)	Active
Mail at rest	Dovecot `mail_crypt` with a global key pair + LZ4 compression (`config/mailer/dovecot/local.conf`, `mail_crypt_save_version = 2`) — every stored message is ciphertext on disk	Active
Archived mail	age client-side encryption to two recipients before upload (Archiving)	Active
Private keys in the DB	Envelope encryption (AES-256-GCM under a file-held KEK) for `dkim_keys.private_key`, `pgp_keys.private_key`, `smime_certs.private_key` (`shared/envelope_encryption.py`)	Active

What the Encryption service provides¶

flowchart LR
    A[Your application] -->|REST| B[Encryption Service :8084]
    B --> C[GnuPG keyrings +\nMySQL key metadata]
    B --> D[WKD: .well-known/openpgpkey\nkey auto-discovery]
    A2[Mail clients / other servers] --> D

API endpoints¶

Text Only

POST   /pgp/generate              # Generate a PGP key pair for a user
POST   /pgp/import                # Import a PGP public/private key
GET    /pgp/keys?email=           # List PGP keys for a user
GET    /pgp/keys/{fingerprint}    # Export a public key (armored)
DELETE /pgp/keys/{fingerprint}    # Delete a key
POST   /pgp/encrypt               # Encrypt a message for a recipient
POST   /pgp/decrypt               # Decrypt with the user's private key
POST   /pgp/sign                  # Sign a message
POST   /pgp/verify                # Verify a signed message
GET    /.well-known/openpgpkey/hu/{hash}   # Web Key Directory serving
POST   /smime/import              # Import an S/MIME certificate
GET    /smime/certs?email=        # List S/MIME certs
GET    /health
GET    /metrics

Key generation and import dispatch encryption.key.generated / encryption.key.imported webhook events.

Web Key Directory (WKD)¶

The service serves PGP public keys at the standard WKD path, so OpenPGP-capable clients (Thunderbird, GnuPG's --locate-keys) can auto-discover a recipient's key from their email address — provided the WKD path is routed on the openpgpkey. host for the domain.

Things to know¶

No automatic encryption in the mail path. There is no milter or filter that encrypts outbound messages when a recipient key is known, and no server-side decryption of inbound PGP mail. Earlier drafts of this page described that as planned; as of 2026-08-30 it remains unbuilt. Clients doing end-to-end PGP/S/MIME work normally — the server just stores and serves keys.
S/MIME support is storage-only. Import and listing of certificates work; there are no S/MIME encrypt/sign operations in the API yet.
The mail_crypt global key is precious. All at-rest mail encryption uses one global key pair mounted into Dovecot (/etc/dovecot/mail_crypt/). Losing it means losing every stored mailbox. Keep it in your backup/escrow path (see Backup & Restore — scripts/escrow-secrets.sh).
mail_crypt_save_version = 2 keeps new mail encrypted. Setting it to 0 would write new mail in cleartext while still reading old ciphertext — only do that as a deliberate move away from at-rest encryption.
Key custody trade-off. Keys generated or imported through this service live on the server (protected by envelope encryption). That enables server-side workflows but means the operator holds the material — for strict end-to-end guarantees, generate keys client-side and only upload public keys.