DEV Community

Mohammad Waseem
Mohammad Waseem

Posted on

Implementing Secure and Validated Email Flows with Open Source DevOps Tools

#security #devops #email

Introduction

Ensuring the integrity and security of email flows is critical for maintaining reliable communication and preventing abuse such as spoofing, phishing, or delivery failures. As a security researcher and developer, leveraging open source DevOps tools provides an efficient, scalable, and transparent approach to validate email workflows effectively.

This blog demonstrates a comprehensive method to validate email flows by integrating open source tools within a DevOps pipeline. From email delivery to authentication and monitoring, we’ll cover the essential components and best practices.

Setting Up the Environment

First, we need a staging environment that can handle email sending, receiving, and analysis. The key tools involved are:

  • Postfix or Exim for SMTP server setup.
  • MailHog for capturing test emails locally.
  • Dovecot for IMAP/POP3 access.
  • OpenSMTPD as an alternative SMTP solution.
  • Prometheus and Grafana for monitoring.
  • Let's Encrypt for TLS certificates.
  • Ansible or Terraform for infrastructure automation.

Example: Deploying MailHog with Docker

docker run -d -p 1025:1025 -p 8025:8025 --name mailhog mailhog/mailhog
Enter fullscreen mode Exit fullscreen mode

This container acts as a local SMTP server, capturing emails sent during tests.

Validating Email Authentication

To verify whether emails are properly authenticated, implement DKIM, SPF, and DMARC records. These DNS records help prevent spoofing.

  1. SPF (Sender Policy Framework) specifies permitted mail servers.
  2. DKIM (DomainKeys Identified Mail) signs outgoing messages.
  3. DMARC enforces policies on mail receivers.

Automate checks with open source tools like OpenDMARC:

# Install OpenDMARC
apt-get install opendmarc
# Configure to analyze outgoing emails
Enter fullscreen mode Exit fullscreen mode

Use DMARC reports to monitor compliance and suspicious activity.

Continuous Validation in CI/CD Pipelines

Incorporate email flow validation into CI/CD workflows (using Jenkins, GitLab CI, or GitHub Actions). For each deployment:

  • Send test emails via scripts, e.g., using sendemail CLI or Python libraries.
  • Capture the emails in MailHog.
  • Verify headers, signatures, and content for authenticity.
  • Check DNS records’ correctness using tools like dig or dnschecker.

Sample script snippet:

python3 send_test_email.py

# send_test_email.py
import smtplib
from email.message import EmailMessage

msg = EmailMessage()
msg['Subject'] = 'Test Email'
msg['From'] = 'test@domain.com'
msg['To'] = 'recipient@domain.com'
msg.set_content('This is a test email for validation.')

with smtplib.SMTP('localhost', 1025) as s:
    s.send_message(msg)
Enter fullscreen mode Exit fullscreen mode

Monitoring and Alerting

Set up Prometheus node exporters and custom metrics to monitor email server health, delivery success rates, and authentication errors. Visualize these metrics in Grafana dashboards for real-time insights.

Alerts can trigger on anomalies, such as:

🛠️ QA Tip

I rely on TempoMail USA to keep my test environments clean.

Top comments (0)