Email Deliverability Fix — From 12% to 97% Inbox Rate

The Problem

A growing Indian e-commerce brand sending 50,000 transactional emails per month (order confirmations, shipping updates, password resets) was seeing only 12% inbox delivery rate. 88% of their emails were going to spam or being rejected outright — causing customer service chaos.

Diagnosis

Our email specialist ran a full deliverability audit and found four critical issues:

• Blacklisted IP: Their sending IP was listed on Spamhaus SBL and SORBS — the server had been used to send spam by a previous owner
• Missing DKIM: No DKIM signature configured — emails failing DKIM check at Gmail, Outlook and Yahoo
• Broken SPF: SPF record existed but listed the wrong mail server IP — all emails failing SPF
• No DMARC: Without DMARC, receiving servers had no policy to apply — defaulting to spam

The Fix

1. Applied for IP delisting from Spamhaus SBL and SORBS — provided evidence of ownership change and clean server
2. Configured OpenDKIM on Postfix with 2048-bit RSA keys
3. Fixed SPF record: v=spf1 ip4:correct.server.ip mx ~all
4. Implemented DMARC starting at p=none for monitoring: v=DMARC1; p=none; rua=mailto:[email protected]
5. Set up DMARC reporting — monitored for 2 weeks
6. Upgraded to p=quarantine then p=reject after confirming alignment
7. Configured Postfix to retry failed deliveries with exponential backoff
8. Set up dedicated sending subdomain: mail.theirdomain.com to separate transactional from marketing email reputation

Results

Inbox delivery rate improved from 12% to 97% within 2 weeks. Both IP blacklistings were removed within 5 business days. DMARC reporting confirmed 100% DKIM and SPF alignment. The client's customer service tickets related to missing emails dropped by 94%.