Open Rate

What is an Open Rate in email?

Open rate is a key metric in email marketing that measures the percentage of recipients who open an email message after it is delivered. It helps organizations assess how effectively their messages capture attention and engage audiences. While not a direct measure of authentication or security, open rate data often interacts with email deliverability, which can be influenced by DMARC, SPF, and DKIM configurations that determine inbox placement.

An email’s open rate depends on multiple factors, including subject line quality, sender reputation, message timing, and mailbox provider filtering. Consistently low open rates may signal deliverability issues, poor content targeting, or messages being routed to spam folders.

How Open Rate Is Calculated

Open rate is calculated as the ratio of opened emails to successfully delivered emails, typically expressed as a percentage:

Example: If 1,000 emails are delivered and 250 are opened, the open rate is 25%.

To track opens, most email platforms embed a small invisible image, often called a “tracking pixel,” in the body of the email. When the recipient’s mail client loads this image, the system records the event as an open. This process, however, can be affected by image-blocking settings, privacy protection tools, or email clients that preload images automatically (such as Apple Mail Privacy Protection), leading to artificially inflated or reduced results.

Factors That Influence Open Rates

Open rates are affected by a combination of technical and content-related variables. Key influences include:

• Sender reputation: Messages from domains with poor reputation or failing DMARC checks are more likely to land in spam folders, lowering opens.
• Subject line and preview text: The clarity, tone, and relevance of the subject line heavily impact whether recipients choose to open.
• List quality: Active, opted-in subscribers are far more likely to engage than stale or purchased lists.
• Authentication setup: Proper SPF, DKIM, and DMARC alignment improves inbox placement and trust, indirectly boosting open rates.
• Send time and frequency: Over-sending can fatigue audiences, while optimized timing increases engagement.
• Device and client behavior: Some mobile clients automatically download images, inflating open metrics.

Because open rate data can be skewed, marketers often pair it with other metrics such as click-through rate (CTR), bounce rate, and conversion rate for a more accurate measure of performance.

Open Rate and Email Deliverability

While open rate is a marketing metric, it reflects deeper deliverability health. A sudden drop in opens can signal authentication problems, RBL listings, or domain misconfigurations. Mailbox providers use sender reputation and authentication status to determine inbox placement. Emails failing authentication or sent from blacklisted IPs are less likely to reach the inbox, leading to low open visibility even if technically delivered.

Maintaining strong deliverability practices can improve open rates over time. This includes:

• Enforcing DMARC with a quarantine or reject policy
• Using properly aligned DKIM and SPF records
• Monitoring blacklists and IP reputation
• Keeping contact lists clean and validated
• Personalizing email content to increase engagement

Open Rate and DMARCeye

DMARCeye helps improve open rates indirectly by ensuring authenticated mail consistently reaches recipient inboxes. The platform identifies authentication failures, misaligned senders, and domain reputation issues that can reduce deliverability - all factors that limit visibility and engagement.

By maintaining compliance with DMARC, SPF, and DKIM standards, DMARCeye helps ensure legitimate messages are trusted and delivered to the primary inbox. This creates a stronger foundation for accurate open rate tracking and sustainable email marketing performance.

Sign up for a free trial of DMARCeye today and secure your email domain.

To learn more about DMARC and DMARC-related terms, explore the DMARCeye Glossary.