SPF Record Expander & Flattener

This PowerShell script retrieves the SPF (Sender Policy Framework) record for a given domain, expands any nested include: and redirect= mechanisms, and then “flattens” the record by converting dynamic mechanisms (such as a: and mx:) into static IP tokens (ip4: and ip6:). It retains other mechanisms (such as exists:, ptr:, and all) as necessary.

Features

• Retrieve SPF Record: Resolves DNS TXT records to extract the SPF record.
• Expand SPF Record: Recursively expands nested include: and redirect= mechanisms.
  • Maximum Recursion: Controlled by the -MaxDepth parameter (default is 5) to prevent infinite loops.
• Flatten SPF Record: Converts dynamic mechanisms:
  • a: Mechanism: Resolves A (IPv4) and AAAA (IPv6) records.
  • mx: Mechanism: Retrieves MX records, then resolves their A/AAAA records.
  • Other Mechanisms: ip4:, ip6:, exists:, ptr:, and all are retained as is.
• DNS Caching: Caches DNS responses to improve performance.
• Configurable DNS Server: Use a custom DNS server (default: 8.8.8.8) via the -DnsServer parameter.
• Debug Output: Enable detailed logging with the -MyDebug switch.
• Base Domain Parameter: Used in the flattening step for mechanisms lacking an explicit domain.

Prerequisites

• PowerShell Version: PowerShell 5.0 or later (or PowerShell Core).
• Network Access: The script requires network access to perform DNS lookups.

Usage

1. Run the Script:

   Open PowerShell and execute the script with the required parameters. For example:

   .\SPFRecordExpander.ps1 -Domain "example.com" [-MyDebug] [-DnsServer "8.8.8.8"] [-MaxDepth 5]