The average email open rate across industries is around 20–25%. If your open rates are below that — or if you want to push above it — there are specific, testable tactics that move the number. This guide covers 12 of them, ordered by impact.
Why open rates matter (and why they're imperfect)
Open rate is the percentage of delivered emails where the recipient opened the message. It's tracked via a 1×1 pixel image. When the image loads, the open is recorded.
Two caveats: Apple's Mail Privacy Protection (MPP), introduced in iOS 15, pre-loads tracking pixels — inflating open rates for Apple Mail users. And open rate alone doesn't tell you whether someone actually read your email. Despite these limitations, open rate trends remain useful for diagnosing list health and subject line performance.
1. Clean your list before optimising anything else
You cannot improve open rates on a dirty list. Hard bounces, spam traps and inactive contacts drag your domain reputation down, which causes Gmail and Outlook to filter your email before recipients even see it.
Run a list audit before any open rate optimisation work:
- Remove all hard bounces immediately
- Suppress all spam complaints
- Segment inactive contacts (no opens in 90+ days) for a re-permission campaign
- Suppress non-responders from the re-permission campaign
A list of 5,000 engaged subscribers will outperform a list of 50,000 unresponsive ones on every deliverability and performance metric. Start here.
2. Warm your sending domain properly
If your domain is new or hasn't sent at scale recently, inbox providers have no sending history to judge it by. Sending high volumes from a cold domain results in bulk filtering — your email lands in spam regardless of subject line quality.
Follow a domain warming schedule: start at 200 sends/day and increase weekly. Monitor bounce and complaint rates throughout. Do not skip this step.
3. Authenticate your domain correctly
DKIM, SPF and DMARC are required by Gmail and Yahoo for bulk senders. Without them, your email is more likely to be filtered or shown with a warning. Authentication failures directly hurt open rates because some emails never reach the inbox at all.
Check all three records are correctly configured before every send. NexusProMail monitors authentication records continuously and alerts you if anything breaks.
4. Segment your list and match content to audience
The single most impactful open rate lever is relevance. An email about GDPR compliance gets different open rates from a marketing team versus a developer — even with the same subject line.
Minimum useful segmentation:
- By engagement level (recent openers vs. cold contacts)
- By acquisition source (web signup vs. event vs. API import)
- By role or industry if you collect that data
Relevant email gets opened. Irrelevant email gets ignored or reported as spam.
5. Write subject lines that create genuine curiosity
Subject lines determine whether your email gets opened. The best subject lines share one characteristic: they make the recipient want to know what's inside. They don't reveal the full answer — they make the answer feel worth having.
Patterns that work:
- The specific number: "7 reasons your emails land in spam" outperforms "Why your emails land in spam"
- The direct question: "Is your domain reputation score above 80?" — creates self-assessment anxiety
- The counterintuitive claim: "Why cleaning your list improves deliverability" — challenges assumptions
- The named problem: "Your unsubscribe rate is telling you something" — speaks to a specific pain
Avoid: emoji overuse, excessive capitalisation, clickbait that overpromises, and subject lines that could trigger spam filters ("FREE!!!", "ACT NOW").
6. Test subject lines with A/B sends
Gut feel about subject lines is unreliable. A/B test two variants on 20% of your list each, wait 4 hours, then send the winner to the remaining 60%. Over time this builds a data-driven picture of what works with your specific audience.
Test one variable at a time: subject line, preview text, sender name, or send time — not multiple at once.
7. Optimise your preview text
Preview text is the snippet shown after the subject line in most email clients. It is the second thing recipients read when deciding whether to open. Most senders ignore it, which means most senders are wasting prime real estate.
Your preview text should extend the subject line — not repeat it, not leave it blank (which causes email clients to pull random body text), and not describe the email ("this week's newsletter"). It should add a second reason to open.
8. Send from a recognisable sender name
Recipients open email from people and brands they recognise and trust. "Ehtisham from NexusProMail" outperforms "NexusProMail" which outperforms "support@nexuspromail.com" as a visible sender name — because it signals a real person wrote this.
Test sender name variations. Some audiences respond better to a personal name, others to the brand name. Know yours.
9. Send at the right time for your audience
General advice about Tuesday morning at 10am is useful as a starting point, not a rule. Your audience's behaviour determines the best send time.
B2B audiences typically engage most on Tuesday–Thursday mornings. B2C audiences vary — weekend and evening sends sometimes outperform weekday sends. Test your specific list rather than applying industry averages.
10. Send consistently — not just when you have something to sell
Sporadic sending damages open rates in two ways. First, recipients forget who you are and mark as spam. Second, inconsistent sending patterns look suspicious to inbox providers.
Send on a regular cadence — weekly, bi-weekly or monthly — and maintain it. Consistent sending builds habit, and habit drives open rates.
11. Re-permission or remove cold contacts
Contacts who haven't opened in 6 months are dragging your average open rate down and hurting your sender reputation. Before suppressing them, run a single re-permission email: "We notice you haven't opened our emails recently. Do you still want to hear from us?" Include a clear call to action to stay subscribed.
Those who don't respond should be suppressed. This improves your open rate (smaller, more engaged denominator), improves deliverability, and reduces the risk of spam complaints.
12. Match email frequency to audience expectations
Sending too often is one of the most common causes of low open rates and high unsubscribes. If your subscribers signed up for a monthly newsletter and you're emailing weekly, open rates will drop.
Set expectations clearly at sign-up ("We send one email per week on email marketing best practices") and honour them. Give subscribers a preference centre to choose their frequency if you have multiple send types.
What to measure alongside open rates
Open rate should never be read in isolation. Track these alongside it:
- Click-to-open rate (CTOR): clicks ÷ opens. Measures subject line relevance vs. email content relevance
- Unsubscribe rate: rising unsubscribes signal frequency or relevance problems
- Spam complaint rate: must stay below 0.08% — anything above signals a list quality problem
- Deliverability rate: if emails aren't reaching inboxes, open rate improvements are meaningless
For deliverability monitoring, see the email deliverability guide and how to monitor email deliverability. For list quality, see contact segmentation.