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Email Deliverability Recovery System

SPF/DKIM/DMARC setup, domain warmup, list cleanup and sender reputation rebuild — from 62% delivery to 96% within 30 days.

2025 Deliverability Engineer Automation

SPFDKIMDMARCDomain WarmupList HygieneSender Reputation

taimoorakhtar.com/projects/email-deliverability-recovery

Introduction

A B2B SaaS client was watching their email open rates collapse from 28% to 9% in three months. Their cold-outbound and customer-update emails were both affected. Postmaster tools showed sender reputation in the red. They thought it was a content problem. It was a deliverability problem.

The Challenge

Deliverability problems compound. Once your domain shows up on a blocklist or your sender reputation tanks, every email after that contributes to the spiral. The client had: missing DMARC record, partial SPF (missing their ESP), no DKIM on the marketing domain, and a contact list that hadn't been cleaned in 18 months — 8% bounce rate per send.

The Solution

Started with auth records. Then quarantined the dirty list and started a fresh warmup process from a separate subdomain. Cleaned the legacy list against a verification API. Monitored sender reputation daily via Google Postmaster Tools and Microsoft SNDS. Rebuilt to healthy sender state within 30 days.

Technical Deep Dive

DNS auth records. Added missing DMARC record (p=none for first 30 days for observation, then p=quarantine). Fixed SPF to include all sending sources without exceeding the 10-lookup limit. DKIM enabled on the marketing subdomain with 2048-bit key.

Domain warmup from clean subdomain. Marketing send moved to mail.client-domain.com — a fresh subdomain with no negative history. Warmed via gradual volume ramp (50/day → 5000/day over 21 days) to engaged segments only.

List hygiene pass. 47K contact list run through ZeroBounce. Catch-all and risky addresses suppressed. 12% of the list flagged as invalid or risky — removed from sending.

Sender reputation monitoring. Daily check on Google Postmaster Tools and Microsoft SNDS. Spam rate, IP reputation, domain reputation all tracked. Anomalies investigated within 24 hours.

Engagement-first sending. First 14 days post-recovery only sent to contacts who'd engaged in the last 60 days. Built positive sender signals before expanding to the full active list.

Key Features

Full SPF/DKIM/DMARC authentication stack
Clean subdomain warmup with engagement-first strategy
List hygiene pass removing 12% of toxic addresses
Daily reputation monitoring with Postmaster Tools and SNDS
Documented runbook for ongoing deliverability hygiene

Results & Impact

Delivery rate: 62% → 96% within 30 days
Open rate recovered from 9% → 31% within 60 days
Domain reputation moved from Bad to High in Google Postmaster
Client now follows a quarterly hygiene cadence to maintain state

Lessons Learned

"Deliverability is auth-records + list hygiene + sender reputation. Skip any one and the others can't compensate."

"When reputation is damaged, switch subdomains and warm fresh. Trying to recover a burned domain costs more than starting clean."

"Engagement-first sending is the fastest path to rebuilding sender reputation. Send only to people who actually want it for 30 days."

Related Work

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