Open Rate

What is Open Rate?

Open rate is the percentage of delivered emails that recipients opened, usually measured when a tiny tracking pixel in the message body loads from the sender's server. It is one of the most widely cited email metrics and a quick proxy for subject line quality and list engagement.

Why it matters

Open rate signals whether your audience cares enough to click at all, and it feeds mailbox provider algorithms that decide inbox placement for future sends. Since Apple Mail introduced Mail Privacy Protection in 2021, open rates have become less reliable, but they remain useful for trend analysis and relative comparison between campaigns. Marketers and lifecycle owners use it daily.

How it works

When a recipient opens an email in a client that loads remote images, a 1x1 transparent pixel hosted by the sending platform is fetched. That request logs the open event with a timestamp and recipient ID. Open rate is then delivered opens divided by delivered messages. Apple Mail preloads images via proxy, so all Apple users now appear to open every email, inflating the number.

Examples

• A SaaS product update with a 34 percent open rate in its onboarding series
• A cold outreach sequence averaging 18 percent, flagging poor subject lines
• A retention campaign whose open rate dropped from 28 to 15 percent after list growth

Best practices

• Test subject lines in small splits before blasting the whole list
• Track unique opens, not total, to avoid double-counting refreshes
• Segment out recipients who never open after 90 days
• Complement open rate with click rate, which is harder to inflate or fake

FAQs

Why are my open rates suddenly higher than before?

Likely Apple Mail Privacy Protection, which prefetches tracking pixels on behalf of users. This artificially raises open rates for any list with significant Apple Mail usage.

Is open rate a reliable metric?

Less than it used to be. Use it as a directional signal alongside clicks, replies, and conversions rather than a precise ground truth.

Do transactional emails need open tracking?

Usually no. Open tracking pixels can trigger spam filters and add no value when you already know the user received a receipt or a reset code.