Newsletter Open Rates Explained: What's Good and Why It Matters

When evaluating a newsletter to sponsor, no metric matters more than the open rate. It determines how many people actually see your placement. This guide explains what newsletter open rates are, what counts as good, what affects them, and why they're central to any sponsorship decision.

What Is a Newsletter Open Rate?

A newsletter's open rate is the percentage of subscribers who open a given issue. If a newsletter has 10,000 subscribers and 4,000 open an issue, the open rate is 40%. It's the clearest measure of how engaged a newsletter's audience actually is.

For sponsorship purposes, the open rate tells you how many people will potentially see your placement — making it the foundation of any evaluation.

What Counts as a Good Open Rate?

Open rates vary by niche and audience type, but general reference ranges help:

• Below 25%: low engagement — proceed with caution and ask why
• 25-35%: average for most newsletters
• 35-50%: strong engagement, indicating a loyal readership
• Above 50%: exceptional, usually smaller tightly-curated newsletters

B2B newsletters often run higher than consumer ones, since professionals read them as part of their work. For audience-specific benchmarks, see our guides on B2B SaaS benchmarks and consumer open rate benchmarks.

What Affects Open Rates

Several factors influence a newsletter's open rate:

• Audience quality — engaged, opt-in audiences open more
• Send frequency — daily newsletters often have lower per-issue rates than weekly ones
• List age and hygiene — older lists accumulate disengaged subscribers
• Subject line quality — strong subject lines drive opens
• How the list was built — organically grown lists tend to engage more than paid-acquired ones

The Apple Mail Inflation Caveat

A crucial caveat: Apple Mail Privacy Protection automatically pre-loads email images, which registers as an "open" even when no one read the issue. This inflates reported open rates for newsletters with significant Apple Mail readership. A reported 55% open rate might reflect a true engaged rate of 35-40%.

When evaluating a newsletter, ask whether their open rate reporting accounts for this. It's one of the most common ways open rates mislead.

Why Open Rate Matters More Than List Size

A common mistake is prioritizing subscriber count over open rate. But a large list with a low open rate can deliver fewer actual views than a smaller list with high engagement. A 10,000-subscriber newsletter at 45% open rate reaches 4,500 people; a 50,000-subscriber newsletter at 15% reaches only 7,500 despite being five times larger — and the smaller one's audience is far more engaged.

Always evaluate open rate and size together, and weight engagement heavily.

Getting Open Rate Data

Open rates come from a newsletter's media kit, which you request from the operator. To compare open rates meaningfully, you need several newsletters in the same category to benchmark against each other — which starts with surfacing a pool of relevant newsletters.

Lettrbase is a newsletter database that lets you surface a pool of newsletters by category, so you can request media kits and compare open rates across real options — identifying the genuinely engaged newsletters worth sponsoring. See our guide to newsletter benchmarks for the full evaluation framework.