Email subject lines that get opened: principles and 30 examples

Your subject line is the one part of your email everyone sees, usually in a glance. The goal is not to be clever. It is to tell the right person, quickly, why this email is worth opening now.

Below: the principles behind email subject lines that work, 30 examples by campaign type, spam-filter myths, and a simple testing routine.

Five principles of subject lines that get opened

1. Clarity beats cleverness

If readers cannot tell what the email is about, many will not open it to find out. Puns and teasers can work for a devoted audience, but clarity is the safer default.

• Weak: "You won't believe this"
• Better: "Our spring collection is live"

2. Be specific

Specific details signal real value: a named product, a date, a concrete benefit, a number that is true.

• Weak: "Big savings inside"
• Better: "20% off all running shoes until Sunday" (only if that is the actual offer)

3. Make it relevant to the reader

The best subject line for one segment can be irrelevant to another. Write for a specific group: new subscribers, recent buyers, people who attended last year's event.

4. Front-load for mobile

Phone inboxes truncate subject lines at a cut-off that depends on the device, app and screen. Put the most important words first so the subject still makes sense if the end gets cut.

• Weak: "We wanted to let you know that our webinar is next Tuesday"
• Better: "Webinar next Tuesday: fixing email bounces"

5. Pair it with the preheader

The preheader (preview text) is the short line shown after or below the subject in most inboxes. Treat the two as one unit: the subject line earns attention, the preheader adds the detail or reason to act.

Leave it empty and many inboxes show your email's first text instead, often "View in browser."

30 subject line examples by campaign type

These examples are generic and brand-neutral. Adapt the details to your business, and only use deadlines, discounts or scarcity when they are real.

Newsletter

1. Your March roundup: 3 ideas worth stealing
2. This month in the workshop: new tools and a quick fix
3. 5-minute read: how we plan a busy week
4. What we learned from our first year
5. {{first_name|Hi there}}, here is your monthly update
6. The one checklist our team uses every Monday

Promotion

7. 20% off everything until midnight Sunday
8. Free shipping this weekend only
9. Your member discount is ready to use
10. Back in stock: the linen shirt you asked about
11. Bundle and save on winter essentials
12. Last day for 15% off annual plans

Announcement

13. Introducing our new booking app
14. We have moved: new address from June 1
15. Now open on Sundays
16. New feature: schedule reports automatically
17. Our updated pricing, explained simply
18. Meet the team behind our new menu

Re-engagement

19. Still want to hear from us?
20. Should we keep sending you emails?
21. Here is what you missed this season
22. {{first_name|Hi}}, a quick question about your inbox
23. We will stop emailing you soon unless you click here
24. A small thank-you for sticking around

Event

25. You are invited: open house on May 14
26. Webinar tomorrow at 2 pm ET: questions welcome
27. Last chance to register for Saturday's workshop
28. Your ticket and directions for Thursday
29. Starting in 1 hour: join the live Q&A
30. Recording inside: missed last week's session?

Spam trigger words: myth vs reality

Lists of "words that send you to spam" circulate widely. The reality is more nuanced.

What genuinely hurts you:

• Fake "RE:" or "FWD:" prefixes. Pretending an email is part of an existing conversation is deceptive, erodes trust and, under CAN-SPAM, subject lines must not mislead recipients about the content of the message.
• ALL CAPS subject lines. They read as shouting and look like spam to people and filters alike.
• Excessive punctuation and symbols. "!!!", "$$$" and rows of emoji look careless.
• False urgency. "Final notice" or "Account suspended" on a marketing email damages trust quickly.
• A mismatch between subject and content. If the email does not deliver what the subject promised, expect complaints.

The fundamentals matter far more than word choice: authenticate your domain, verify your list so you are not bouncing off dead addresses, and send content people want. Our guide on how to improve email deliverability covers the full picture.

Personalization with merge tags and fallbacks

Personalization helps when it is relevant. A first name is the simplest option; relevance to what someone bought or signed up for often matters more.

Always use a fallback so contacts without the data do not see a blank or a raw tag. In InboxRoads, merge tags support fallbacks like this:

• Hi {{first_name|there}}, new ideas for your week becomes "Hi Sam, new ideas…" or "Hi there, new ideas…" and reads well both ways.
• Avoid {{first_name|there}}, your order is ready: without a name it becomes "there, your order is ready." Always read the fallback version out loud.
• New for the {{company|your}} team works for B2B lists.

Check how many contacts actually have the field filled in, keep names clean on import, and do not overuse the first name; it loses effect when every email has it.

How to test your subject lines

Send tests to yourself first

Before every campaign, send a test email and look at it on a phone and a desktop. Check that:

• The subject and preheader read well together and are not cut off in a confusing place.
• Merge tags render correctly, including the fallback.
• The sender name is recognizable.

Run A/B tests in general terms

An A/B test sends two subject line versions to separate random samples of your list, then compares results. To get a useful answer:

1. Change one thing at a time, such as specific vs general, question vs statement, or with vs without a number.
2. Use samples large enough that a difference is not just noise. Small lists may need to test across several campaigns instead.
3. Pick the winner on clicks or conversions, not only opens.
4. Record what you learn so each test builds on the last.

Measure with the Apple Mail Privacy Protection caveat

Since Apple introduced Mail Privacy Protection in 2021, Apple Mail can preload images in emails, which registers as an open whether or not the person read the message. That makes open rates inflated and less reliable, especially if many of your subscribers use Apple Mail.

• Treat open rates as a directional signal and compare against your own past campaigns.
• Use click rate and conversions as your main measure of subject line success.
• Watch unsubscribes and complaints: a subject line that wins on opens but raises complaints is not a winner.

FAQ

How long should an email subject line be?

Long enough to be clear, short enough to survive truncation on a phone. Put the essential words first and check your test send on a mobile device.

Should I use emoji in subject lines?

One relevant emoji can help an email stand out, but it should add meaning, not decoration. Test how it renders across devices, and avoid replacing key words with symbols.

Do subject lines affect deliverability?

Indirectly. Deceptive or spammy subject lines drive complaints, and complaint rates affect whether future emails reach the inbox. Authentication, list quality and engagement matter more.