Saphira Linux MailDragon

MailDragon encrypts stored mail on disk using Dovecot mail_crypt with AES-256-GCM. Newly written mailbox files no longer expose ordinary headers or body text when searched directly on disk, while mail is decrypted transparently for authorised IMAP and webmail access.

By default MailDragon uses a server-managed global key. The mail server holds the key needed to read mail, so day-to-day operation and support work are unaffected. The next hardening stage moves the private key into a runtime-only location so the permanent filesystem holds only sealed or offline key material.

A key rotation is a migration, not a replacement. It is complete only when new mail is written under the new key, old mail has been read through Dovecot and rewritten under the new key, a test environment proves the rewritten mail reads with only the new key, a test environment proves old encrypted data cannot be read without the old key, and backups have been migrated or consciously retained. Only then is the old key removed from live use — and even then it is safely archived until retention policy allows destruction.

A hardening step is not considered done until recovery has been tested. The recovery pack records key fingerprints, holds an offline encrypted copy of every private key still needed for retained mail, includes the active configuration, and documents the restore procedure and the date it was last tested.

MailDragon can offer customer-controlled encryption keys as an advanced option. If a user controls their own key, passphrase, hardware token or recovery key and loses it, the encrypted mail cannot be recovered — not because support will not help, but because of the mathematics of the encryption model.

A mailbox owner can request a usable export of their own mail. Decryption happens only through Dovecot, and exports are produced as cleartext Maildir, mbox, or a compressed archive with a manifest and checksums — so a user can take their data elsewhere. The export location is locked down as soon as it is written.

Storage encryption protects mail at rest. PGP protects selected message contents from the server itself. The two are separate: mail_crypt guards the mailbox store, while PGP is optional and user-driven for the messages that need it. Lost PGP keys, like lost user-held storage keys, can mean lost message contents.

No live mailbox encryption migration, rotation, decryption or user-key feature is used on production mail until it has been proven against a large test corpus and restore-tested end to end. The guiding rule is simple: encryption must never become mailbox loss. Data is only successfully encrypted when it stays both confidential and recoverable by its rightful owner.