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B2B Outbound · International Deliverability Recovery

Inbox Placement from 34% to 87% After Full DNS and Authentication Rebuild

Nearly 2 in 3 emails were never reaching the inbox. The authentication stack had multiple critical failures, the primary business domain was being used for cold sending, and a major blacklist entry was silently blocking delivery. All of it was diagnosable and fixable.

34%
Inbox placement rate before the audit
87%
Inbox placement rate after the rebuild
72h
Blacklist cleared and re-verified
100%
Authentication stack passing after rebuild
The Situation

What Was Happening

Zafar was running B2B cold email campaigns and seeing consistently low reply rates. Open rates were being reported, but replies were minimal — suggesting emails were either going to spam or not being seen at primary inbox placement. A full inbox placement test revealed that only 34% of sends were landing in the primary inbox. The remaining 66% were going to spam, promotions, or being blocked entirely. The exact failure points were not visible from inside the sending tool.

The Diagnosis

Root Cause

The Problem

SPF record was failing due to too many DNS lookups — the 10-lookup limit was exceeded, causing SPF to fail silently on a significant percentage of sends. DKIM selector in the sending tool did not match the published DNS record, causing DKIM failures on all authenticated sends. DMARC policy was set to 'none', providing no enforcement and no reporting. The primary business domain was being used for cold email sending with no separation. One major blacklist entry was confirmed, silently blocking delivery to a significant portion of Gmail and Outlook recipients.

The Fix

SPF record flattened to resolve the lookup limit issue. DKIM keys regenerated with the correct selector matching the sending tool. DMARC policy set to quarantine with weekly aggregate reporting. Primary domain removed from cold email sending entirely and dedicated secondary domains set up. Blacklist removal request submitted, confirmed cleared within 72 hours. Warmup ramp restarted from scratch across new sending domains. Placement testing confirmed at 87% after rebuild.

The Work

What Was Built

01
Inbox Placement Audit

GlockApps placement test run to establish baseline — 34% primary inbox, remainder going to spam or blocked. Seed test data used to identify which providers were failing and at what rate.

02
SPF Flatten and Rebuild

SPF record lookup count confirmed at 13 — over the 10-lookup limit. Record rebuilt using SPF flattening to resolve all includes into direct IP ranges, eliminating lookup depth issue.

03
DKIM Regeneration

DKIM selector mismatch identified between DNS record and sending tool configuration. New DKIM keys generated. DNS record updated. Sending tool reconfigured to use correct selector. Verification confirmed.

04
DMARC Policy Enforcement

DMARC updated from none to quarantine. RUA reporting address added for weekly aggregate reports. Policy change allows enforcement to begin while still receiving visibility on legitimate send failures.

05
Blacklist Clearance

Primary domain confirmed listed on Spamhaus SBL. Removal request submitted with documented fix evidence. Confirmed delisted within 72 hours. Re-test run and confirmed clean.

06
Secondary Domain Setup

Dedicated cold email sending domains acquired. Primary business domain removed from cold outreach entirely. Authentication stack built on new domains from scratch.

07
Warmup and Re-Test

New mailboxes enrolled in warmup ramp. Three-week warmup completed. GlockApps placement test re-run — 87% primary inbox confirmed across Gmail and Outlook before campaign reactivation.

Tools Used

Tech Stack

GlockAppsMXToolboxMail-TesterCloudflareGoogle WorkspaceSpamhausBarracuda
The Result

Outcome

Inbox placement moved from 34% to 87% after the full rebuild. SPF, DKIM, and DMARC all passing. Primary business domain protected from cold email risk. Blacklist cleared within 72 hours. Warmup completed and placement verified before any campaign volume was reintroduced. The system now has a monitoring cadence to catch future degradation before it becomes a deliverability failure.

34% to 87% inbox placement. Authentication fully passing. Blacklist cleared in 72 hours.

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