Apple MPP inflates this number. Pair with click_to_open_rate for a truer engagement signal.
At a glance
The percentage of delivered emails that were opened, aggregated across every campaign and Customer Journey email sent in the period. Computed asSUM(unique_opens) ÷ SUM(emails_sent) × 100from thereports.opensblock on each campaign report. Apple’s Mail Privacy Protection inflates this metric. UK consumer lists with heavy iOS Mail usage routinely report 50-70% open rates that are 30-40% higher than actual reads. Pair with Click-to-Open Rate for a truer engagement signal.
Calculation
Calculated automatically from your Mailchimp data. See the At a glance summary above for what the metric tracks and the worked example below for a typical reading.Worked example
A non-profit charity newsletter on Mailchimp with a single audience of 24,000 subscribers (predominantly UK consumer, mixed iOS/Android/desktop). The 30-day window covers 03 Apr 26 to 02 May 26.
Five observations:
- The headline 64.8% looks fantastic but ~25-30% of those opens are MPP robots. UK charity lists often skew older and more iOS-heavy than typical DTC. Strip out the MPP inflation and the real open rate is closer to 45-50%, still healthy for a non-profit but not the trophy figure the dashboard suggests. Always pair this card with Click-to-Open Rate and Click Rate, MPP doesn’t fake clicks.
- The Customer Journey thank-you email opens at 76.7%, the highest in the account. This is normal: triggered transactional-style emails are highly anticipated by the recipient (they just donated, they expect a confirmation), so genuine open intent is high AND MPP inflates further. Customer Journey opens routinely beat broadcast campaigns by 10-15 percentage points.
- The volunteer reminder beat the broadcast appeals slightly. This is typical of segmented sends, the volunteer reminder went to a smaller, more engaged sub-audience. List-based blast vs segmented send efficiency shows up here. Mailchimp’s list-first model means small segmented sends like this require more setup than they would on Klaviyo, but the engagement payoff is similar.
- A 1% drop-off from 65% to 64% is not significant. Open-rate noise band is roughly ±2-3 percentage points week-over-week on a list this size. Don’t chase the daily figure. Watch the 30D rolling vs the prior 30D, the alert threshold is <10% which is a different order of magnitude.
- The same campaigns sent 12 months ago (pre-MPP) would have shown 38-45% open rates. Historical comparisons across the iOS 15 boundary (Sep 2021) are unreliable. If you have a “but our open rate used to be 40%” reference point from before late 2021, the apples-to-apples replacement metric is now click rate, not open rate.
Sibling cards merchants should reference together
Open rate is MPP-noisy. Pair it with these for real engagement signal:Reconciling against the vendor’s own dashboard
Where to look in Mailchimp’s own dashboard: Mailchimp → Audience → All Contacts → Recent Activity for per-subscriber open history, and Mailchimp → Campaigns → Reports for the per-campaign Open Rate metric. The headline tile on each campaign report shows “Opens” and “Open rate”, and the Audience Overview panel shows the rolling rate. This card sums opens and sends across every campaign + Customer Journey email in the period to one figure; figures should match this card to within ±0.2 percentage points. Other Mailchimp views that look like the same number but aren’t:- Audience → Settings → Audience health: a different “open rate” computed against the audience’s most recent send only. Different denominator.
- Reports → Comparative Reports: ad-hoc selection. Defaults differ from this card’s “every campaign + automation in window” rule.
- Customer Journeys → individual journey → email step: per-email-step open rate, not aggregate.
Cross-connector reconciliation:
Open rate is a Mailchimp-internal engagement metric. There is no commerce-platform or analytics tool that surfaces a directly comparable figure. The closest cross-references:
Known limitations / merchant FAQs
Why is my open rate 65%? Is that real? Almost certainly not. Apple Mail Privacy Protection pre-fetches images server-side, firing the open pixel without any human reading the email. UK consumer lists with heavy iOS Mail usage routinely show 50-70% open rates that are inflated by 30-40% over the genuine read rate. Your “real” open rate is closer to 40-45%. Use Click Rate and Click-to-Open Rate for the MPP-resistant truth. Why are my open rates lower than Klaviyo’s? They might not be, properly. Both ESPs use unique-opens with image pixels, both are MPP-affected. The most common cause of a lower Mailchimp blended rate is list-wide blasts (Mailchimp’s default sending pattern) vs segmented sends (Klaviyo’s default). A list-wide blast hits dormant subscribers who don’t open; a segmented send only hits engaged subscribers who do. Restructure sends by segment in Mailchimp to close the gap. My open rate dropped 10 percentage points. What happened? Three usual causes: (a) you imported a large batch of new subscribers without confirmation, diluting the engaged base; (b) a deliverability problem dropped you into the spam folder for one major ISP (typically Gmail), where opens still fire but at lower volume; (c) you changed sending domain or sender name, breaking subscriber recognition and triggering low engagement on the first few sends. Open Mailchimp → Account → Sender Reputation to check, and pause sends if reputation has dropped below “Good”. What’s a healthy open rate for Mailchimp specifically? Post-MPP (i.e. since late 2021), the “healthy band” for consumer DTC on Mailchimp is roughly 30-45%, but the band is misleading because of the MPP inflation. A more honest framing: a healthy Mailchimp account has Click Rate >2% and Click-to-Open Rate >8%. If those two are healthy, raw open rate is window dressing. The alert threshold here (<10%) is set deliberately low because below that, even MPP can’t save you, the list is genuinely dead. Why do triggered Customer Journey emails open higher than broadcast campaigns? Triggered emails are anticipated. The customer just signed up, just abandoned a cart, just placed an order, they’re expecting the email and engaged with the brand at the moment. Broadcast campaigns interrupt; triggers respond. Customer Journey opens of 50-80% are normal and don’t require a benchmarking adjustment. Does this card include opens from automation/Customer Journey emails? Yes. This card sums opens and sends across regular campaigns, A/B test variants, and every Customer Journey email step that delivered in the period. Why is my today value volatile? Today’s open rate is computed against partial-day sends. If you sent at 09:00 UTC and it’s now 12:00 UTC, MPP pre-fetches have fired but human opens through the day haven’t accumulated. Treat today as directional only. Does Mailchimp distinguish MPP opens from real opens? No. Unlike some ESPs that flag pre-fetched opens server-side, Mailchimp’s API returns a singleunique_opens figure with no MPP attribution. To estimate the inflation, look at the gap between Open Rate and Click-to-Open Rate, if your CTOR is <8% but your open rate is >50%, MPP is doing most of the work.
What about plain-text or images-blocked clients, do they under-count?
Yes. Corporate Outlook with images-off is the classic case, recipients open and read the email but the pixel never fires, so they’re invisible to this metric. B2B audiences are 20-40% under-counted on opens for this reason. Don’t penalise B2B campaigns for “low” open rate; check the click rate instead.