smtpfirewall

SMTP Firewall

SMTP Firewall serves as a sidecar container alongside your primary application. It filters emails before they reach your email service provider.

Key features:

• Rate Limit with a mail queue
• Dropping emails if the app sends too frequently to a single recipient
• Bad Domain Filter
• Support SMTP and multiple email service providers

Getting started

Using a Docker Compose file

Instead of running SMTP Firewall as a sidecar in a Kubernetes Pod, you may make use of Docker Compose to try running it.

version: '3'

services:
  smtp:
    image: rnwood/smtp4dev
    ports:
      - 3000:80
  smtp_firewall:
    image: relatedbits/smtp-firewall
    environment:
      FILTER_BAD_DOMAIN_ENABLED: true
  app:
    image: YOUR_APPLICATION_IMAGE # Replace with your app image
    environment:
      SMTP_HOST: smtp_firewall # Set SMTP Host
      SMTP_PORT: 1025          # Set SMTP Port

Launch the containers using:

docker compose up -d

Open your application and send an email.

You may then open http://localhost:3000 to see if the email is being dropped.

Prepare an email blacklist

SMTP Firewall reads from bad_domains.txt for the email blacklist. Each line in the file represents a domain name.

You may start from downloading email blacklist online:

• https://github.com/disposable-email-domains/disposable-email-domains

Select an email service proviers

SMTP

Environment variables:

AWS SES

Environment variables:

Mailjet

Environment variables:

Configuration

Environment variables