GitHub Action

RustMail provides a GitHub Action for email assertion in CI pipelines.

Quick Start

- name: Start RustMail
  uses: rustmailapp/rustmail-action@v1

- name: Run tests (your app sends emails to localhost:1025)
  run: npm test

- name: Assert emails were sent
  uses: rustmailapp/rustmail-action@v1
  with:
    mode: assert
    assert-count: 1
    assert-subject: "Welcome"

The action has two modes:

1. start (default) — Downloads the RustMail binary, starts an ephemeral SMTP server in the background, and waits until it's ready.
2. assert — Checks captured emails against your filters using the REST assertion API.

Inputs

Start Mode

Input	Default	Description
mode	start	Set to start (or omit — it's the default)
smtp-port	1025	SMTP port to listen on
http-port	8025	HTTP/API port
version	latest	RustMail version (e.g., v0.1.0)

Assert Mode

Input	Default	Description
mode	—	Set to assert
assert-count	1	Minimum number of matching emails
assert-subject	—	Filter by subject substring
assert-sender	—	Filter by sender address
assert-recipient	—	Filter by recipient address

Outputs

Output	Description
http-port	HTTP port the server is listening on
smtp-port	SMTP port the server is listening on

Full Workflow Example

name: E2E Tests

on: [push]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Start RustMail
        uses: rustmailapp/rustmail-action@v1
        with:
          smtp-port: 1025
          http-port: 8025

      - name: Run tests
        run: npm test
        env:
          SMTP_HOST: 127.0.0.1
          SMTP_PORT: 1025

      - name: Assert welcome email
        uses: rustmailapp/rustmail-action@v1
        with:
          mode: assert
          assert-count: 1
          assert-subject: "Welcome"

      - name: Assert password reset email
        uses: rustmailapp/rustmail-action@v1
        with:
          mode: assert
          assert-count: 1
          assert-subject: "Password Reset"

Multiple Assertions

Chain as many assert steps as you need. Each one checks independently against the same running server:

- uses: rustmailapp/rustmail-action@v1
  with:
    mode: assert
    assert-count: 1
    assert-subject: "Order Confirmation"

- uses: rustmailapp/rustmail-action@v1
  with:
    mode: assert
    assert-sender: "noreply@example.com"
    assert-count: 3

Pinning a Version

By default the action downloads the latest RustMail release. Pin to a specific version for reproducibility:

- uses: rustmailapp/rustmail-action@v1
  with:
    version: v0.1.0

TIP

For non-GitHub CI systems, use the CLI Assert Mode or REST Assertions directly.