Resources
This page provides additional resources to deepen your understanding of SMTP security, including standards, research papers, books, and online courses.
The core SMTP specification that defines the protocol's operation and commands.
Defines how STARTTLS is implemented in SMTP for securing connections.
Specifies how authentication mechanisms are used with SMTP.
Describes the email authentication method designed to detect forging sender addresses.
Defines a method for email authentication using cryptographic signatures.
Provides a framework for email authentication, policy handling, and reporting.
Recommended Reading Path
For those new to SMTP security, we recommend the following learning path:
- Start with the basics - Read RFC 5321 to understand how SMTP works
- Learn about security extensions - Study RFCs for STARTTLS, Authentication, SPF, DKIM, and DMARC
- Study common vulnerabilities - Review "The Ultimate Guide to SMTP Vulnerabilities" [^4]
- Explore advanced attacks - Read "SMTP Smuggling" research paper [^5]
- Practice in lab environments - Set up vulnerable SMTP servers in a controlled environment
- Join communities - Engage with other security professionals to share knowledge
Creating a Lab Environment
To practice SMTP penetration testing safely, consider setting up a lab environment:
- Virtualization - Use VirtualBox, VMware, or Hyper-V to create isolated virtual machines
- Docker - Use containers to quickly deploy different SMTP server configurations
- Vulnerable VMs - Download purposely vulnerable virtual machines from VulnHub or similar platforms
- Network isolation - Ensure your lab network is completely isolated from production environments
Staying Current
SMTP security is an evolving field. To stay current:
- Subscribe to security mailing lists focused on email security
- Follow CVE announcements for SMTP server software
- Participate in bug bounty programs that include email infrastructure in scope
- Attend security conferences and workshops that cover email security topics