54% Open Rates Across 2.5 Million Emails

2024-03-01

54.8% avg open rate across 203 campaigns and 2.5M sends

Consistently above-average engagement maintained at serious scale, with 205 active automated flows running in parallel.

The challenge

Scaling email without sacrificing deliverability or engagement is one of the hardest problems in email marketing. Most large programs see open rates drop as volume grows. This brand was already sending at scale: hundreds of thousands of emails per month, 205 active flows, a mature Klaviyo setup. The goal was not to build something new but to hold 50%+ open rates as volume continued to grow. The risk at this stage is complacency. When something works, the temptation is to leave it alone. But email deliverability degrades without maintenance: unengaged contacts accumulate, domain reputation drifts, and open rates quietly erode. Keeping rates above 54% across 2.5 million sends required constant attention to segmentation discipline, list hygiene, and testing — not periodic, but ongoing every week.

Approach

• Built strict engagement-based segmentation: every campaign targeted a specific sub-audience by open recency (30/60/90 days), purchase behavior, and product interest. No send to the full list.
• Ran suppression flows on a rolling basis: contacts approaching churn were flagged early and moved to a re-engagement sequence before they disengaged completely
• 205 automated flows maintained and optimized: each flow reviewed quarterly for conversion rate and revenue contribution — underperforming flows revised or replaced
• Subject line and preview text tested on every campaign: minimum 100 recipients per variant, winner sent after 3 hours. No exceptions.
• Domain reputation monitored monthly: tracked bounce rates, spam complaint rates, and inbox placement. Proactive response to any signal before it compounded.
• Send cadence adjusted per segment: high-engagement contacts received more volume, low-engagement contacts received less — preventing list fatigue across a large subscriber base
• 203 campaigns managed alongside 205 flows with a structured content calendar to prevent timing conflicts and contact overlap between automation triggers and manual sends

Results

• 54.8% — avg open rate (industry avg: 25%)
• 3.67% — avg click rate (industry avg: 2.5%)
• 2,516,217 — total emails delivered
• 205 — active automated flows

Tools used

Klaviyo, Email Automation, List Segmentation, Deliverability, A/B Testing

Key insight

At this volume, open rate performance is determined in the first 60 minutes of a send. If a campaign isn't performing in the first hour, the subject line and preview text have failed. The discipline that held 54.8% open rates across 2.5 million sends was consistent testing, not intuition — every subject line was tested on a small segment before the full send, and we were willing to swap the subject line mid-send when the data was clear. Click rate at 3.67% across this volume is harder to maintain than open rate. That held because every email was sent to a list that had already demonstrated interest in the specific category being promoted.