Open rate plotted over time. Apple Mail Privacy Protection auto-opens make the absolute level meaningless, so read the shape of the line, not the number on it.
At a glance
The time-series of email open rate across the selected period, one point per period bucket. Each point is opens_unique ÷ delivered for sends in that bucket. Since Apple’s Mail Privacy Protection (MPP) pre-fetches images and registers an open whether or not a human looked, a large and unknowable share of these opens are machine opens. Treat the absolute level as inflated and the trend line as directional. A sudden step-change down in this line is far more diagnostic than the headline percentage, it usually flags a deliverability or inbox-placement problem rather than a sudden loss of human interest.
| What it counts | Open rate per period bucket, opens_unique ÷ delivered × 100, plotted as a line over the selected window. |
| API endpoint + statistics field | POST /api/campaign-values-reports (and GET /api/metric-aggregates for the Opened Email metric) returning the open_rate statistic, derived from opens_unique over delivered. |
| Email vs SMS aggregation | Email only. SMS has no open concept, so SMS sends are excluded from both numerator and denominator. |
| MPP impact | Heavy. Apple MPP auto-opens inflate opens_unique, so the absolute level overstates real human opens, often by 20-40 percentage points for iOS-skewed lists. The trend is still useful because the MPP share is roughly stable week to week. |
| Chart type | Line. |
| Time window | 30D vsP |
| Alert trigger | A sustained downward step in the trend (rather than a fixed level), which typically signals inbox-placement or reputation issues. |
| Roles | owner, marketing |
Calculation
Calculated automatically from your Klaviyo data. See the At a glance summary above for what the metric tracks and the worked example below for a typical reading.Worked example
An illustrative homeware brand sending two to three Klaviyo campaigns a week. Reading the dashboard on 14 Apr 26 for the trailing 30 days (14 Mar 26 to 12 Apr 26), the open-rate line by week looks like this (figures are illustrative, not a real merchant’s data):| Week | Delivered | Unique opens | Open rate |
|---|---|---|---|
| 14-20 Mar 26 | 41,200 | 18,950 | 46.0% |
| 21-27 Mar 26 | 43,800 | 19,710 | 45.0% |
| 28 Mar-3 Apr 26 | 40,500 | 14,580 | 36.0% |
| 4-12 Apr 26 | 44,100 | 19,400 | 44.0% |
- The 46% headline is inflated by MPP and should not be read as “46% of humans opened”. For an iOS-skewed homeware audience, a large slice of those opens are Apple Mail pre-fetches. The useful information here is that the line normally sits around 45%, not that the level is high.
- Week 3’s drop to 36% is the real signal. A nine-point step down in a single week, against an otherwise flat line, is the kind of move worth investigating. Because MPP opens are roughly constant, a drop this size usually means fewer messages actually reached the inbox (more landed in spam or Promotions, or a deliverability dip), not that humans suddenly lost interest.
- Always pair the step-down with delivery-rate and bounce data. If Delivery Rate also dipped in week 3, that confirms an inbox-placement story. If delivery held steady, the cause may instead be a weak send (a poorly targeted segment or a dull subject line) rather than a systemic problem.
- Week 4 recovering to 44% suggests the week 3 dip was transient. A one-week dip that self-corrects is common after a single underperforming campaign. A two- or three-week sustained decline is the pattern that warrants escalation to a deliverability review.
- For a cleaner human-interest read, cross-check the click line. Clicks are not MPP-affected, so if Click Rate Trend is flat while this open line wobbles, the wobble is almost certainly MPP noise or inbox placement, not a change in real engagement.
Sibling cards merchants should reference together
Open Rate Trend is a directional engagement signal. Pair it with these to separate MPP noise from real movement:| Card | Why pair it with Open Rate Trend |
|---|---|
| Email Open Rate | The single-period headline behind this line. The trend tells you the shape; the headline tells you the latest reading. |
| Click-to-Open Rate | The MPP-resistant complement. CTOR isolates how compelling the content was for people who actually opened, which the raw open rate cannot. |
| Opened Trend | The volume view of the same metric. A rising open rate on falling volume tells a very different story than a rising rate on rising volume. |
| Engagement Funnel | The full delivered, opened, clicked, converted cascade. Use it to see where in the funnel an open-rate dip actually bites. |
| Deliverability Drop | The most likely cause of a sustained open-rate step-down. Check this card first when the line drops and stays down. |
| Email Click Rate | The cleaner engagement signal. Clicks are real human actions and not inflated by MPP, so they confirm or contradict an open-rate move. |
Reconciling against Klaviyo
Where to look in Klaviyo:- Klaviyo → Analytics → Performance, then the open-rate metric over time, for the account-level trend.
- Klaviyo → Campaigns, then open a campaign to see its individual open rate, useful for attributing a trend dip to a specific send.
- Klaviyo → Analytics, then the Opened Email metric in Metric reporting, which underlies the rate.
| Reason | Direction of divergence |
|---|---|
| Time zone. Vortex IQ buckets by UTC day; Klaviyo reports in your account time zone. Sends near midnight can fall into a different bucket. | Either direction, usually marginal. |
| Period boundaries. Vortex IQ uses a 30-day rolling window vs prior; Klaviyo dashboards often default to calendar months. | Either direction. |
| Page caps. Campaign-values reporting pages at 50 records, so very high-volume accounts may see slight aggregation truncation in a single pull. | Reported rate runs marginally off for very large senders. |
| MPP auto-opens. Both systems count machine opens, but Klaviyo offers an MPP filter toggle in some views. If you have it on in Klaviyo and we do not, the numbers diverge. | Klaviyo’s filtered view reads lower. |
| Campaign vs flow scope. If the Klaviyo view you compare against is campaigns-only while ours blends campaigns and flows (or vice versa), the rates differ. | Either direction. |