# ADR 0005 — Oracle Cloud as the launch host, and what it forbids

**Status:** Accepted, 2026-09-02.

## The constraint

**OCI blocks outbound TCP/25 for every tenancy created after 2021-06-23.**
Exemption is a service-limit request, routinely refused for free tier. Inbound
:25 is *not* blocked.

| | On OCI |
|---|---|
| Receive on :25 | ✅ works — `openmail-smtpd` is fine |
| Relay out on 587 | ✅ works (verify: see below) |
| Direct-to-MX | ❌ **impossible.** `mail-dane` and `mail-mta-sts` can never run there |

## Decision

Launch on OCI in **split delivery**: receive directly, relay outbound. Support
Oracle Cloud Email Delivery *and* SES as relay providers from day one — two
providers at launch forces the provider abstraction to be genuinely
data-driven instead of an SES-shaped `if`.

Direct-to-MX (v0.4) is developed and tested on a host without the block.

## Consequences

- Embedded inbound moves from "milestone 4, later" to **required at launch**.
- The relay path is not a temporary on-ramp; on our own launch host it is the
  only outbound path that exists.
- Oracle's SPF include is region-scoped (`rp` / `eu.rp` / `ap.rp`
  `.oracleemaildelivery.com`), so `providers.rs` deliberately stores `None` and
  makes the operator paste theirs. A guessed include turns the DNS check green
  against a mechanism the provider does not honour and mail still fails SPF —
  silently. Same for Resend.

## ⚠️ Open — verify before committing to the host

Oracle's docs name only port 25. Mailcow community reports claim **587 and 2525
are also blocked outbound on free tier**, which would make OCI unable to relay
either, and would change the host choice entirely.

**Test on a free instance before building on this.** It is a 20-minute check
and it invalidates this ADR if the reports are right.