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Karti TripathiandClaude Opus 5 36b15ddcaf Rewrite as a Rust, Apache-2.0 workspace

Supersedes the Go + embed-Mox design. The Go tree is removed; its
architecture doc is preserved at docs/archive/ARCHITECTURE-go-embed-mox.md
because its competitive analysis and data model still hold.

Five decisions recorded as ADRs:

  0001  Rust, not Go — accepting ~5,500 lines of protocol code that Mox
        would have given us free, to get the first permissively licensed
        Rust mail server. Costs stated plainly.
  0002  Apache-2.0, not MIT or AGPL — patent grant, trademark, CLA-free
        contribution. Public on GitHub; Gitea stays as the private fallback.
  0003  Stalwart's primitive crates (Apache-2.0/MIT) yes; its AGPL server
        crates never. DANE and MTA-STS sit on the AGPL side of that line,
        which is why we write our own.
  0004  Milestones, reordered: embedded inbound is required at launch.
  0005  Oracle Cloud blocks outbound :25, so direct-to-MX is impossible on
        the launch host. Split delivery is mandatory, not an on-ramp.

Twelve crates in three tiers. Tier 1 (mail-dane, mail-mta-sts, mail-dsn)
is standalone and publishable — no `dane` or `mta-sts` crate exists on
crates.io at all today.

openmail-relay ships the provider table as data, with SES and Oracle from
the start. Oracle's and Resend's SPF includes are deliberately None: a
guessed include turns the DNS check green against a mechanism the provider
does not honour, and mail still fails SPF silently.

cargo check/test/clippy/fmt all green; unsafe_code is forbidden workspace
wide; cargo-deny enforces the licence policy in CI.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JkyvfNJGTshJNE9FtwPLk7

2026-09-02 13:08:05 -07:00

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ADR 0002 — Apache-2.0

Status: Accepted, 2026-09-02. Supersedes the MIT choice in the archived architecture (§8).

Decision

Apache-2.0, and the repository is public on GitHub (karti-ai/openmail). The Gitea mirror (OSS/openmail) stays as the fallback if the project ever needs to go private.

Why not MIT

Same freedoms, but Apache-2.0 adds three things that matter here:

§3, express patent grant. Email authentication is a standards thicket — DKIM, DKIM2, ARC, DMARC. MIT's patent grant is implicit at best, and that is what enterprise legal review flags.
§6, trademark reservation. "OpenMail" is a generic name with at least three unrelated projects already using it. Apache-2.0 protects the name while the code stays free.
§5, contributor terms. Inbound contributions are licensed on the same terms without a separate CLA.

Inbound compatibility is clean: every dependency is Apache-2.0 or MIT.

Why not AGPL

AGPL + a commercial exception is the standard way to protect a future hosted offering — it is exactly what Stalwart does (AGPL-3.0-only OR LicenseRef-SEL). We reject it because it makes us unusable by the commercial agent builders who are the intended audience, and because being the permissive option is the entire competitive position. Stalwart's AGPL is the reason its competitors must run it in a sidecar; we do not want to be that for someone else.

Consequences

"No GPL/AGPL/LGPL anywhere" remains policy, but the reason changed. Under MIT it was a compatibility fact; under Apache-2.0 it is a deliberate choice, since Apache-2.0 is one-way-incompatible with GPL-2-only. Enforced in CI by cargo-deny.
Every source file gets no licence header (the LICENSE + NOTICE pair is sufficient and headers rot); NOTICE must be shipped with any redistribution and lists third-party attribution.
Anyone may fork this closed. That is the intent, not a leak.

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