The open rate indicates what percentage of the people who received your email opened it. It is one of the first metrics people look at in a campaign. It is closely tied to the email subject line, the sender, the time of delivery, and the prior relationship with the customer.

Why does it matter?

It serves as an early warning sign: if almost no one opens the email, none of its content will be effective. It helps you compare subject lines, send times, and segments.

But you have to read it carefully. Some email clients, for privacy reasons, automatically download the content of emails, even if the recipient never opens them. This can register opens that didn’t actually happen and inflate the open rate. That’s why it’s best to use it to compare trends—not as proof of success—and to supplement it with click-through rates and, above all, sales.

How is it calculated?

Formula: Open rate = (emails opened ÷ emails delivered) × 100

For example, if you send 10,000 emails, 500 bounce, 9,500 are delivered, and 1,900 people open them, the open rate is 1,900 ÷ 9,500 × 100 = 20%. Delivered emails are used, not sent emails, because an email that bounced never had a chance to be opened.

Story mode

An online sports store tests two subject lines for its running campaign. The second one, “Lucía, your next pair of running shoes is waiting for you,” gets more opens than the generic one. The team celebrates, but then reviews the sales and notices that the difference in purchases is smaller than the open rate suggested. Learn to use the open rate as a clue, not as the final result.

How to Use It with Data4Sales

At Data4Sales, open rates are a useful metric, but not the goal. What you measure is business:

• The attribution report shows the revenue for each campaign and channel.
• The control (holdout) group allows you to calculate actual incremental revenue: what you sold as a result of the campaign, not clicks or opens.
• With Segments and Orbis Creative, you can send messages tailored to each customer—which is what really drives open rates and purchases.

Related terms

• Email marketing
• CTR
• Deliverability
• Incremental revenue