Ever wondered what happens after you hit “send” on your email campaign? I mean what REALLY happens – not just how many opens or clicks do you get, but what’s the story behind them? How fast do people open or click, are all opens equal, is there a way to reduce unsubscribes by changing the send time…
To challenge my own assumptions, I decided to analyze a sample of over 10 million email sends from the past 3 months to uncover more granular insights into user behavior. I’ve learned that opens can be very delayed, some clicks are more important than others, and not all metrics happen at the same rate.
If you want to know more, let’s dive in.
Analysis methodology
Before I start, here’s a brief outline on the analysis methodology.
The data for this analysis is based on over 10 million email sends for an eCommerce brand. While this is a relatively small sample size to represent a serious cross-industry benchmark, I believe it represents email engagement trends pretty accurately based on my experience working with 30+ brands.
Being pragmatic, the emails in this analysis are split into AM sends (9am) and PM sends (8pm) with a goal of understanding the potential differences in engagement caused by the send time. The data tracks three key metrics – opens, clicks, and unsubscribes – over a period of 7+ days.
The data (opens, clicks…) are represented in cumulative percentages, not absolute metrics. For example, 86% opens on day 1 would mean that 86% of the all that email had happened by day 1.
Email Engagement Over Time
Let’s look at how email engagement unfolds over time (cumulative):
| Days after send | Opens | Clicks | Unsubscribes |
| Day 0 (until midnight) | 61.4% | 74.2% | 78.6% |
| Day 1 | 86.3% | 91.7% | 92.9% |
| Day 2 | 90.8% | 94.3% | 95.2% |
| Day 3 | 93.2% | 95.9% | 96.4% |
| Day 4 | 94.5% | 96.8% | 97.1% |
| Day 5 | 95.4% | 97.4% | 97.8% |
| Day 6 | 95.8% | 97.8% | 98.1% |
| Day 7 | 96.2% | 98.1% | 98.3% |
| After Day 7 | 3.8% | 1.9% | 1.7% |
Most of the engagement happens on the first day – up until midnight. Unsubscribes and clicks are more immediate actions than opens. By the end of send day, nearly 80% of unsubscribes have happened, while opens take longer to accumulate – with some engagement trickling in even after a month.
Practically speaking, this shows us that the first day or two are the most important because that is when 90%+ of the engagement comes in, but the reality is even more striking when looking at the hourly breakdown:
| Time after send | Opens | Clicks | Unsubscribes |
| First hour | 16.7% | 41.9% | 47.1% |
| By hour 2 | 27.9% | 59.3% | 66.3% |
| By hour 4 | 34.3% | 67.8% | 75.4% |
| By midnight | 61.4% | 74.2% | 78.6% |
| By end of Day 1 | 86.3% | 91.7% | 92.9% |
What’s most striking here is that even though the first hour accounts for only 16% of total opens, it accounts for 42% of clicks!
This tells us something crucial about email engagement – if someone’s going to click or unsubscribe, they usually do it right after they receive the email. All opens take a while to come in, but those coming in hours and days after the send are “low quality” opens.
Additionally, morning sends also show an interesting pattern – a second engagement spike during evening hours (7-9 PM), suggesting subscribers return to their inboxes after work.
Comparing AM vs PM Sends
Brands send emails at different times of the day, so let’s take a look at how morning vs. evening send time impacts the metrics:
| Calendar Day | Opens | Clicks | Unsubscribes | |||
| 9:00 AM | 6:00 PM | 9:00 AM | 6:00 PM | 9:00 AM | 6:00 PM | |
| Day 0 (until midnight) | 61.4% | 42.1% | 74.2% | 53.8% | 78.6% | 56.2% |
| Day 1 | 86.3% | 82.4% | 91.7% | 89.3% | 92.9% | 90.8% |
| Day 2 | 90.8% | 89.2% | 94.3% | 93.1% | 95.2% | 94.4% |
| Day 3 | 93.2% | 92.1% | 95.9% | 95.2% | 96.4% | 96.1% |
| Day 4 | 94.5% | 93.8% | 96.8% | 96.4% | 97.1% | 97.0% |
| Day 5 | 95.4% | 94.9% | 97.4% | 97.2% | 97.8% | 97.6% |
| Day 6 | 95.8% | 95.5% | 97.8% | 97.6% | 98.1% | 97.9% |
| Day 7 | 96.2% | 96.0% | 98.1% | 98.0% | 98.3% | 98.2% |
| After Day 7 | 3.8% | 4.0% | 1.9% | 2.0% | 1.7% | 1.8% |
The key difference is that PM sends show significantly lower same-day engagement simply because they have fewer hours until midnight. That is a crucial downside of PM sends if you require same-day engagement. PM sends catch up to the AM sends in terms of engagement only 2 days after the send.
Let’s compare the hourly engagement patterns between morning and evening sends during those crucial first hours.
| Time After Send | Opens | Clicks | Unsubscribes | |||
| 9:00 AM | 6:00 PM | 9:00 AM | 6:00 PM | 9:00 AM | 6:00 PM | |
| First hour | 16.7% | 17.2% | 41.9% | 29.7% | 47.1% | 28.2% |
| By hour 2 | 27.9% | 24.5% | 59.3% | 44.6% | 66.3% | 40.1% |
| By hour 4 | 34.3% | 31.8% | 67.8% | 52.9% | 75.4% | 48.6% |
| By midnight | 61.4% | 42.1% | 74.2% | 53.8% | 78.6% | 56.2% |
| By end of Day 1 | 86.3% | 82.4% | 91.7% | 89.3% | 92.9% | 90.8% |
This tells us something crucial about the impact of send time – morning sends drive much faster engagement, especially for clicks and unsubscribes. Evening sends see similar open rates initially but much lower click and unsubscribe rates, suggesting people are more likely to save the email for later.
The Conclusion
The data shows clear patterns that can guide your email strategy. Morning sends drive faster engagement but have two peaks – immediate and evening hours. Evening sends show more concentrated initial engagement but take longer to reach their full potential.
Key takeaways:
- Wait at least 4 hours before assessing campaign performance.
- Consider 48 hours as the final engagement window – if someone hasn’t clicked by then, they likely never will.
- Use morning sends for time-sensitive content, evening sends for complex offers.
- When comparing AM vs PM performance, remember that Day 0 metrics will look worse for PM sends.
- Send time doesn’t affect total achieved metrics, just the amount of time it takes to achieve them.
This understanding of engagement patterns allows you to better plan your campaigns, set appropriate expectations, and optimize your email operations.