Eternals Mailer

Eternals Mailer is an email testing tool for developers. It captures emails sent by your application during development so you can inspect them in a clean web UI. Point your app’s SMTP config at Eternals Mailer, and every outgoing email lands in your local inbox — safely, instantly.

Built with Go for SMTP capture, a NestJS API, a React web UI, PostgreSQL for persistence, and Redis for caching, Mailer lets you view HTML/text bodies, headers, and attachments for every captured email. No emails leave your environment, making it perfect for development and QA testing.

How to Use This Image

Quick Start

docker run -d \
  --name ec-mailer \
  --restart always \
  -p 8502:8502 \
  -p 1025:1025 \
  -e POSTGRES_URL=postgresql://postgres:password@host:5432/mailer \
  -v mailer:/app/attachments \
  eternalscloud/mailer:latest

Once the container is running:

• Web UI: Open http://localhost:8502 in your browser
• SMTP Server: Configure your application to send mail to localhost:1025

Docker Compose

services:
  ec-mailer:
    image: eternalscloud/mailer:latest
    container_name: ec-mailer
    restart: always
    ports:
      - "8502:8502"
      - "1025:1025"
    environment:
      - POSTGRES_URL=postgresql://postgres:password@db:5432/mailer
    volumes:
      - mailer:/app/attachments
    depends_on:
      - db

  db:
    image: postgres:18.4
    restart: always
    environment:
      POSTGRES_PASSWORD: password
      POSTGRES_DB: mailer
    volumes:
      - postgres:/var/lib/postgresql/data

volumes:
  mailer:
  postgres:

Run with:

docker compose up -d

Environment Variables

Exposed Ports

Volumes

Mount a volume to /app/attachments to persist email attachments across container restarts.

Need more? See the full documentation for SMTP client examples and integration guides.