Email subject lines that get opened: 30 templates and what the data says
Thirty fill-in subject lines in six types, plus ready-made subject and preview-text pairs for common emails, what the data says, and how to test without trusting open rates.
A subject line gets opened when it’s clear, specific and relevant to the reader, and when the sender name and preview text back it up. Klaviyo’s data puts the average subject line at about seven words. Write the subject and preview text as a pair, front-load the important words for mobile, and never promise something the email doesn’t deliver. Below are 30 templates in six types. Test them on clicks, not opens, because Apple Mail Privacy Protection inflates open rates.
- People decide from three things together: the sender name, the subject line and the preview text. Write all three.
- Klaviyo reports that subject lines average about seven words, and that first names appear in only around 2.5% to 3.4% of them.
- Apple Mail Privacy Protection can register opens automatically, so judge subject lines on clicks and results.
- Under the US CAN-SPAM Act, the subject line must accurately reflect the content of the email. Honest beats clever.
Key terms explained (12)
- CAN-SPAM
- The US federal law that sets the rules for commercial email.
- FTC
- The US Federal Trade Commission, the agency that enforces CAN-SPAM.
- Snippet
- The short description shown under a page’s title in search results.
- Conversion
- When a visitor does what you want them to do, such as booking, buying or filling in a form.
- Open rate
- The share of people who opened an email. Apple Mail can register opens automatically, so treat it as a rough guide.
- Click rate
- The share of people who clicked a link in an email. A more reliable sign of interest than opens.
- Preview text
- The short line shown after the subject line in the inbox, before someone opens the email.
- Deliverability
- How reliably your emails land in the inbox instead of the spam folder.
- Segment
- A group of contacts who share a behaviour or trait, so they can get messages that fit them.
- Machine opens
- Email opens registered automatically by an email app such as Apple Mail, not by a person reading the email.
- Hook
- The opening of a video or post, usually the first one to three seconds or first line, written to make people keep watching or reading.
- Swipe file
- A saved collection of examples, such as subject lines or hooks, with notes on how each performed.
What decides whether an email gets opened?
When someone scans their inbox, they see three things for each email: who it’s from, the subject line and the preview text. They decide in about a second. A great subject line from a sender they don’t recognise still gets skipped, and a good subject line with “View this email in your browser” as its preview text wastes half its space.
So the job isn’t to write a clever line. It’s to make those three pieces work together and tell the reader, honestly, why this email is worth opening now.
What does the data say?
- Length. Klaviyo’s subject line analysis says subject lines across business sizes average about seven words, including emojis. There’s no magic number. What matters is that the important words come first, because phones cut the line short.
- First names. The same analysis found first names in only about 2.45% of small business subject lines and 3.35% for mid-market brands. Personalisation by situation (“your booking”, “your quote”) is usually more useful than a name.
- Emojis. Klaviyo found around 42% to 43.5% of businesses use emojis in subject lines. One relevant emoji can help a line stand out; three in a row looks like a sale flyer.
- Preview text. Knak’s guide recommends 40 to 90 characters with the most important words in the first 40, since mobile apps may cut it at 30 to 55 characters. If you leave it empty, the email app shows the first text it finds, often “View this email in your browser”.
Why you can’t trust open rates
Since Apple introduced Mail Privacy Protection in late 2021, Apple Mail can load an email, and its tracking pixel, before a person reads it. Twilio SendGrid reported a 24.8% increase in unique opens across its customers after the launch, from these “machine opens”. Open rates still help you spot a sudden drop, but use clicks, replies and bookings to decide which subject line won.
How to use the templates
Replace the words in square brackets. Three rules:
- Match the email. The FTC’s CAN-SPAM compliance guide says the subject line must accurately reflect the content of the message. Misleading lines also cost trust and future opens.
- Be specific. “3 fixes for a contact form nobody fills in” beats “Website tips”.
- Use real numbers. The examples are illustrations. Only use figures you can back up.
Inbox preview
Type your sender name, subject line and preview text to see roughly how they sit in a phone inbox.
Every phone and mail app cuts text at a different point, so treat this as a rough guide and send yourself a test.
Type 1: Clear benefit
| # | Template | Example |
|---|---|---|
| 1 | How to [result] in [time] | How to get 10 more reviews this month |
| 2 | [Number] ways to [result] | 5 ways to fill your Tuesday appointments |
| 3 | Your [thing], [improved] | Your quote, simplified |
| 4 | The easiest way to [result] | The easiest way to book your yearly check-up |
| 5 | [Result] without [pain] | More leads without a bigger ad budget |
Type 2: Curiosity, used honestly
| # | Template | Example |
|---|---|---|
| 6 | The [thing] most [people] get wrong | The website mistake most contractors make |
| 7 | Why [common belief] isn't working | Why boosting posts isn't bringing customers |
| 8 | I tested [A] against [B] | I tested two landing pages for a month |
| 9 | What [experts] know about [topic] | What busy clinics know about no-shows |
| 10 | Before you [action], read this | Before you renew your ad budget, read this |
Type 3: Personal and plain
These look like an email from a person, which they should be.
| # | Template | Example |
|---|---|---|
| 11 | Quick question, [first name] | Quick question, Maria |
| 12 | About your [thing] | About your kitchen quote |
| 13 | [First name], is this still a priority? | James, is this still a priority? |
| 14 | Following up on [topic] | Following up on Tuesday's call |
| 15 | Can I help with [thing]? | Can I help with your website launch? |
Type 4: Timely, with a real reason
Urgency works only when it's true. A fake deadline teaches people to ignore the next one.
| # | Template | Example |
|---|---|---|
| 16 | [Event] starts [day] | Spring bookings open Monday |
| 17 | Last day for [offer] | Last day for 15% off furnace tune-ups |
| 18 | [Number] spots left for [thing] | 4 spots left for March installs |
| 19 | Reminder: [thing] on [date] | Reminder: your appointment on Thursday |
| 20 | Before [season or deadline] | Before the first frost: 3 checks for your home |
Type 5: Numbers and lists
| # | Template | Example |
|---|---|---|
| 21 | [Number] [things] to [do] this [period] | 3 marketing tasks to finish this month |
| 22 | [Number]-minute [fix] for [problem] | A 10-minute fix for slow email replies |
| 23 | [Number] questions to ask before [decision] | 7 questions to ask before hiring a contractor |
| 24 | The [number]-step [process] | The 4-step follow-up we use after every quote |
| 25 | [Number] [results] from [period] | What 12 months of email taught us |
Type 6: Questions
| # | Template | Example |
|---|---|---|
| 26 | Are you [making a mistake]? | Are you sending customers to your home page? |
| 27 | Do you know [fact]? | Do you know where your leads come from? |
| 28 | What would [result] mean for you? | What would 5 more bookings a week mean? |
| 29 | Still [problem]? | Still chasing quotes by phone? |
| 30 | Ready for [next step]? | Ready for your spring clean-up? |
Subject and preview pairs for common emails
| Subject line | Preview text | |
|---|---|---|
| Welcome | Welcome, here's what happens next | Three things to know, and how to reach me directly |
| Booking confirmation | You're booked for Tuesday at 10 | Here's what to bring and where to park |
| Quote follow-up | About your kitchen quote | A quick answer to the question most people ask |
| Newsletter | 3 fixes for a contact form nobody fills in | Number 2 takes five minutes |
| Offer | Last day for 15% off tune-ups | Book any time before midnight tonight |
| Re-engagement | Should I keep sending these? | One click to stay, or I'll stop emailing |
The re-engagement email matters for deliverability. I explain why in email segmentation strategy.
How do you test subject lines?
- Test one change at a time: two subject lines, same email, same send time.
- Send each version to an equal random share of the list, then the winner to the rest. Most email tools do this automatically.
- Pick the winner on clicks or replies, not opens.
- Keep a swipe file of every subject line with its click rate. After a few months you'll see which types your audience responds to.
The same idea drives short-form video openings. If you write social content too, my 30 social media hooks use the same patterns.
What mistakes should you avoid?
- All capitals and multiple exclamation marks. They look like spam, to people and to filters.
- Fake "Re:" or "Fwd:". Misleading, and it breaks trust.
- Empty preview text. Always write it.
- The same formula every time. Rotate types so readers don't tune out.
- Judging by opens alone. Clicks and replies tell you what worked.
Tools for the job
| Tool | Use it for | Cost |
|---|---|---|
| Mailchimp | A/B testing subject lines and preview text | Free plan |
| Klaviyo | Subject line tests and click-based reporting | Free plan |
| GoHighLevel | Email campaigns alongside your CRM and texts | Paid |
| Litmus | Previewing how emails look across inboxes | Paid |
| Mail Tester | Checking an email for spam signals before sending | Free |
Plans and pricing change. Check each tool's site for current details.
Frequently asked questions
How long should an email subject line be?
There's no fixed rule. Klaviyo reports an average of about seven words. Put the most important words first, because mobile email apps cut long subject lines short.
Should I use the recipient's first name in the subject line?
Sometimes. Klaviyo found first names in only about 2.5% to 3.4% of subject lines. Referring to the reader's situation, such as their booking or quote, is often more useful than a name.
What is preview text and how long should it be?
Preview text is the snippet shown after the subject line in the inbox. A common recommendation is 40 to 90 characters, with the key words in the first 40. If you leave it empty, the email app shows the first text it finds.
Are open rates still reliable?
Not on their own. Apple Mail Privacy Protection can register opens automatically, which inflates open rates. Use clicks, replies and conversions to judge subject lines.
Can a subject line be misleading if it gets more opens?
It shouldn't be. Under the US CAN-SPAM Act, the subject line must accurately reflect the content of the email, and misleading lines also damage trust and future opens.
Related playbooks
Browse every playbook on email marketing, or see all marketing playbooks.
Sources
- Email subject lines and open ratesKlaviyo
- How email senders are adapting to Apple Mail Privacy ProtectionTwilio
- Email preview text: length, character limits and examplesKnak
- CAN-SPAM Act: a compliance guide for businessFederal Trade Commission
- Frequently asked questions about Canada's anti-spam legislationCRTC
Remar Catapang is a full-funnel marketing strategist based in Ontario, Canada. He has worked in marketing since 2020 and continues to lead search, CRM automation, web, paid media and experiential campaigns for businesses in Canada, the United States, Australia, Egypt and the Philippines. His playbooks are based on that ongoing work. Questions about this playbook: remarcatapangjr@gmail.com
