email deliverability audit

The problem

Major mailbox providers like Google, Yahoo, and Microsoft now enforce strict authentication and list-hygiene requirements for bulk senders. If your setup is misconfigured, your emails won't just land in spam, they will be rejected at the gateway with 5.7.x error codes.

What it does

• Calculates true bulk-sender status by aggregating volume across all streams (marketing, transactional, notifications) over rolling 24-hour windows.
• Audits DNS records for SPF, DKIM, and DMARC compliance, specifically checking for the alignment between the From domain and authenticated identifiers.
• Validates RFC 8058 one-click unsubscribe headers to ensure they meet the specific HTTPS POST requirements rather than just "manage preferences" pages.
• Assesses sending hygiene, including PTR (reverse DNS), TLS transmission, and spam complaint rate monitoring against the 0.10% threshold.
• Identifies provider-specific enforcement phases, such as Microsoft's phased transition from Junk-routing to outright rejection.

Frameworks & tools

Google Postmaster Tools, Microsoft SNDS, SPF, DKIM, DMARC, RFC 8058, DNS.

Why this beats prompting it yourself

Most basic prompts fail to account for the "permanent" nature of bulk-sender status or the nuance of domain alignment versus simple record presence. This skill uses a governed snapshot of provider policies to ensure you aren't relying on outdated 2023 or 2024 thresholds that have since evolved.

Use cases

• Pre-flighting a new sending domain before ramping up outreach volume.
• Diagnosing why transactional emails are suddenly bouncing with 5.7.x authentication errors.
• Confirming if a 3,000/day sender is actually a "bulk sender" due to aggregated cross-platform streams.
• Automating technical deliverability audits for agency clients during onboarding.

Known limitations

Internal complaint rate and reputation data require existing access to Postmaster Tools or SNDS. This audit focuses on technical compliance, not content-based spam filtering.