Summary

This guide explains how to integrate SPF (Sender Policy Framework) with DuoCircle's DNS and email services. It includes configuration instructions, troubleshooting tips, and recommendations for optimal security. For more information on SPF, visit OpenSPF.

Objective

By following this guide, you will:

  • Learn to configure SPF records for DuoCircle services.
  • Optimize your email security.
  • Troubleshoot common SPF issues.

Introduction

SPF is a vital email authentication mechanism that helps prevent spoofing and ensures your emails are delivered securely. This guide focuses on configuring SPF records for DuoCircle's Standard SMTP, Email Gateway, and Backup MX services.

Prerequisites

  • Access to your domain's DNS settings.
  • Familiarity with SPF syntax and configuration.
  • Relevant permissions for DNS modifications.

Step-by-Step Instructions

1. Configuring SPF for DuoCircle Standard SMTP

Customers using DuoCircle's Standard SMTP service to send email for their domain can configure an SPF record to authorize DuoCircle's servers.

  1. Add the following SPF record to your domain’s DNS configuration:
    "v=spf1 include:outbound.mailhop.org ~all"

    This record allows your domain to use DuoCircle's SPF settings for outbound.mailhop.org.

  2. Recommendation: Use the stricter -all mechanism instead of ~all for enhanced protection.
    • The -all setting rejects email from IPs not explicitly listed in your SPF record.
    • Before switching to -all, ensure your SPF record includes all legitimate email providers. Otherwise, valid mail may be lost.

2. Troubleshooting SPF Record Validation

If you receive errors when validating your SPF record:

Consult the Common SPF Verification Problems guide for troubleshooting steps.

3. Addressing SPF Record Limitations

When combining DuoCircle's SPF record with another provider, you may exceed the 10 DNS lookup limit. 

In such cases:

Flatten your SPF record as described in this guide.

4. Configuring SPF for DuoCircle Email Gateway and Backup MX

For customers using DuoCircle's Email Gateway or Backup MX services:

  • Configure your systems to “skip” SPF checks for DuoCircle servers.
  • Use DuoCircle's SPF records rather than specific IP addresses. This ensures service reliability, even if DuoCircle relocates its servers.

5. Skipping SPF Tests for Specific IPs

Consult the documentation for your Mail Transfer Agent (MTA) or SPF implementation to learn how to skip SPF checks for specific IP addresses.

Conclusion

By configuring SPF for DuoCircle services, you improve email security and reduce spoofing risks. Use the resources provided in this guide to troubleshoot and optimize your SPF configuration effectively.