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
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ADR 0003 — Write our own crates; use Stalwart's primitives, never its server
Status: Accepted, 2026-09-02.
The licence boundary
Stalwart Labs ships two distinct things:
| Licence | Us | |
|---|---|---|
The server (stalwartlabs/stalwart, crates/*) |
AGPL-3.0-only OR LicenseRef-SEL |
❌ never |
The primitives (mail-parser, mail-auth, mail-builder, mail-send, smtp-proto) |
Apache-2.0 OR MIT |
✅ dependencies |
DANE and MTA-STS live in crates/smtp and crates/common — on the AGPL side
of that line. That is precisely why we write our own.
Rule
- Depending on the permissive primitive crates is fine and intended.
- Reading the AGPL server crates for understanding is fine.
- Copying, adapting or transliterating any line from them is not, and would
contaminate the whole workspace. When implementing DANE or MTA-STS, work from
the RFCs (7672, 8461, 6698) — not from
stalwart/crates/smtp. - The research mirror at
~/Desktop/ProjectMail/mail-servers/stalwartis read-only reference. Same formaddy(GPL-3) andBillionMail(AGPL).
Which of our crates get published
Tier 1 (mail-dane, mail-mta-sts, mail-dsn) are published standalone: they
depend on nothing in this workspace, they fill real holes in the ecosystem, and
their value to us is partly that other projects audit them. Names verified
available on crates.io 2026-09-02, as is openmail itself — reserve early.
Tier 2 and 3 stay in-workspace until their APIs settle.