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Sources and method

Every claim on this site that carries the folded corner, with how it was established. When a figure changes, its date changes with it.

Folded corner: the claim carries a source, printed at the foot of the cell.

  1. 1

    500,000 messages per mailbox, index search in 58 ms

    FoldBench, FOLD's own benchmark runner, against a synthetic mailbox of 500,000 messages; full-text query over the SQLite FTS5 index; median of five runs.

    Environment
    Apple M1 Ultra · macOS 27.0 · release build
    As of
    2026-09-22
  2. 2

    3,044 automated tests in engine and interface

    Count of Swift Testing (@Test) and XCTest functions: engine package 2,257, interface package 747 plus 40. The last full run of both suites documented green was 2026-09-17; on 2026-09-22 the engine suite ran green, the interface suite had two failures in a test group that depends on window focus.

    Environment
    Xcode 27.0 · Swift 6.4
    As of
    2026-09-22
  3. 3

    0 third-party packages in engine and interface

    The dependency lists of both Swift packages (engine and interface, 103,361 lines of Swift) are empty; every import is an Apple system framework. The app shell of the direct download adds one package, the Sparkle updater.

    Environment
    Package.swift of both packages
    As of
    2026-09-22
  4. 4

    95 RFCs cited in the source code

    Distinct RFC numbers referenced in the Swift sources of engine and interface. A citation points to the standard a piece of code implements or is checked against; it is not a conformance certificate. The standards page lists the ones a mail client is measured by, with their implementation status.

    Environment
    Source tree of engine and interface
    As of
    2026-09-23
  5. 5

    58 ms · 0.7 ms · 9 ms · 67 s at 500,000 messages

    FoldBench storage-engine timings: full-text query, 50 message headers read from SQLite, opening the store with its first index snapshot, and ingesting 500,000 messages into the header store. App cold start, frame time and memory are budgeted but not yet instrumented.

    Environment
    Apple M1 Ultra · macOS 27.0 · release build · median of five runs
    As of
    2026-09-22
  6. 6

    Fortress Mode: Argon2id, HKDF, AES-256-GCM

    Argon2id and BLAKE2b are FOLD's own implementations, checked in the test suite against the test vector of RFC 9106 and against the argon2 reference tool. HKDF and AES-GCM come from CryptoKit.

    Environment
    Automated tests
    As of
    2026-09-22
  7. 7

    S/MIME: sign, verify, encrypt, decrypt

    The test suite reads messages and certificates generated with openssl smime; messages written by FOLD were checked against openssl by hand. CMS per RFC 5652 with RSA and AES-CBC; AES-GCM from RFC 8551 is not supported yet.

    Environment
    Automated tests
    As of
    2026-09-23
  8. 8

    OpenPGP: Ed25519 and Curve25519, legacy contained

    Decryption and signature checks in the test suite against messages and keys generated with GnuPG (Ed25519, Curve25519, RSA); rejection of messages without integrity check (EFAIL) is tested explicitly. Messages written by FOLD were checked against GnuPG by hand. RFC 9580, version 4 keys.

    Environment
    Automated tests
    As of
    2026-09-23
  9. 9

    DKIM computed on your machine

    Ed25519 byte for byte against the example of RFC 8463 Appendix A; RSA against an openssl-signed fixture; keys under 1024 bits rejected per RFC 8301.

    Environment
    Automated tests
    As of
    2026-09-22

Internal file references and raw measurements are kept in the fact check of this site; ask [email protected] if you want to see them.