Crate http_smtp_rele 

http-smtp-rele: minimal, secure HTTP-to-SMTP submission relay.

Architecture

External Client
  | HTTPS POST /v1/send
Reverse Proxy / TLS Endpoint
  | HTTP localhost
http-smtp-rele
  | SMTP localhost:25
OpenSMTPD / SMTP Server

Responsibility: auth, validation, sanitization, rate limit, SMTP submission.

Re-exports

pub use request_id::RequestId;

Modules

api

HTTP API router and middleware wiring.

auth

Authentication and access control.

config

Configuration loading and validation.

error

Application error types, ErrorCode enum, and HTTP response mapping.

logging

Logging initialization using tracing and tracing-subscriber.

mail

Safe plain text mail construction.

metrics

Prometheus metrics instrumentation.

policy

Recipient domain and API key permission policy.

rate_limit

Three-tier token bucket rate limiting: global, per-IP, per-key.

request_id

Application-owned request identifier.

sanitize

Header injection detection and sanitization.

security

Platform security hardening.

smtp

SMTP relay transport.

status

Submission status tracking — types, errors, and store abstraction.

status_memory

In-memory submission status store (RFC 087).

validation

Request validation pipeline.

Structs

AppState

Shared application state, cloned into every Axum request via Arc.