An opt-in receive-only SMTP listener (PICLOUD_SMTP_BIND) so an MX can point
straight at PiCloud. It speaks minimal SMTP (HELO/EHLO/MAIL/RCPT/DATA/RSET/
NOOP/QUIT), resolves each RCPT TO mailbox to the app-owned email trigger that
claims it, and inserts an Email outbox row the dispatcher fires — the same tail
as the HMAC webhook, unchanged.
- migration 0076: email_trigger_details.inbound_address (case-insensitively
unique among app triggers) + TriggerRepo::email_inbound_target_by_address /
SmtpInboundTarget; the interactive create-email API accepts inbound_address.
- crates/picloud/src/smtp.rs: a small tokio accept loop + session state machine
+ a testable deliver() core + a minimal RFC-5322 header/body split. DATA is
size-capped with dot-unstuffing; no AUTH/STARTTLS (TLS terminates upstream —
the recipient address + per-app isolation are the boundary).
- spawned in run_server alongside axum::serve, sharing the pool, on the same
shutdown signal.
Pinned by a picloud integration test (deliver → one Email outbox row for a
known mailbox, none for an unknown one) + smtp.rs unit tests (address parse,
header/body split). Multipart/MIME decoding is a documented follow-up.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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