Interview Questions › Root Cause Analysis

Email open rates have dropped for your weekly newsletter

Your platform's flagship weekly digest open rate dropped from 38% to 24% over the last 3 editions. Diagnose the deliverability and engagement drop.

Context

List size grew by 20% recently following a viral cross-promotion campaign.

Clarifying questions to ask first

• Did open rates drop across all email clients or specifically Gmail Promotions tab?
• Did unsubscribe or spam complaints increase?

How to approach it

1. Segment open rates by Email Client (Gmail, Apple Mail, Outlook, Yahoo)
2. Analyze Sender Domain Reputation, DMARC/DKIM authentication, and Spam Complaint Rates
3. Evaluate cohort engagement (Tenured subscribers vs New viral leads)
4. Check subject line testing, send time changes, and email clipping issues in Gmail

Framework: Email Client / Domain Deliverability -> Cohort Quality (New vs Old) -> Subject Line & Preview Text -> Technical SPF/DKIM Config

Sample answer

• Emails routed to Gmail Spam/Promotions tab due to increased promotional links
• New viral subscriber cohort had low engagement intent
• HTML payload size exceeded 102KB causing Gmail to clip the tracking pixel

1. Check Deliverability by Client: Apple Mail and Outlook steady at 40%, Gmail dropped from 39% to 12%
2. Investigation reveals email template redesign increased HTML file size to 115KB, clipping the open pixel in Gmail

Gmail message clipping hid tracking pixel and hurt sender score; minified HTML template under 80KB to restore tracked open rates.

What interviewers look for

• Unique Open Rate (%)
• Deliverability to Primary Inbox (%)
• Spam Complaint Rate
• Unsubscribe Rate