Email subject lines that say what is inside, with examples by purpose

Good email subject lines tell the reader what the email contains and why it matters to them today, in the first few words, and nothing in the email contradicts them. The FTC’s CAN-SPAM guide says it in one line: “Don’t use deceptive subject lines.” Below are original examples grouped by what the email is for, and the rules that sit behind them.

Every example on this page was written for this page. None of them comes with an open rate, because the only honest way to know which subject line works for your list is to send two of them to your list. Where an example names a deadline, it is marked, because a deadline in a subject line is a promise.

What a subject line has to do in the inbox

A subject line is never read alone. In most inbox lists it sits between the sender name and a line of preview text, and the reader takes in all three at once before deciding to open, scroll past or delete.

That changes how you write it. The sender name already says who you are, so the subject does not need to repeat your brand. The preview text can carry the second half of the thought, so the subject does not need to fit everything. In the example above, the subject names the offer and the deadline, and the preview text gives the code.

What Gmail, Yahoo and the FTC say about misleading subject lines

Three documents a sender in the US should know set the outer limits, and they agree with each other:

The FTC guide also says each separate email that breaks the law can draw penalties of up to $53,088, a figure it updated for inflation in January 2024. The Gmail line about “Re:” and “Fwd:” is the most specific subject line rule in these documents, and it rules out a trick that still turns up in promotional mail: dressing a campaign up as a reply so it looks like part of a conversation.

None of these documents says a subject line must be short, polite or free of capitals. They say it must be true.

How to write an email subject line, step by step

1. Write down what the email is for, in one sentence. “Tell people the sale ends Sunday” is a purpose. “Drive engagement” is not.
2. Name the thing the reader gets or has to do. An order number, a product, a discount, a date. Specific nouns do more work than adjectives.
3. Put the important words first. A phone screen is narrower than a desktop window and the cut moves with font size, so whatever comes last is the part most likely to go missing.
4. Use the preview text for the second half. Write it on purpose rather than letting the first line of your template (“View this email in your browser”) fill it.
5. Check it against the email. If the subject says “ends Sunday”, the email says when on Sunday, and the offer really ends then.
6. Send two versions to a slice of your list if your platform supports a split test, and keep the one that wins on your own readers.

Which words get capitals is a separate decision, with its own rules and one spam filter rule; email subject lines capitalization covers it.

Email subject line examples, grouped by purpose

These are examples written for this guide, for an invented clothing store. Swap the nouns for your own. The column on the right marks the ones that only work if a real deadline sits behind them.

Promotional email subject lines

For a sale that runs over several sends, sale email subject lines gives a line for each one, from the teaser to the final hours.

Announcements and launches

Reminders and events

The email a new subscriber gets first has its own job, delivering what the sign-up form promised; welcome email subject lines has examples for each kind of sign-up.

Transactional and account emails

A cart reminder also goes to one person about one thing, but it asks for a sale rather than confirming one. Abandoned cart email subject lines covers the reminder, the help email and the last nudge.

Transactional subjects are the easiest to write, because the reader is already waiting for the thing they name. Gmail’s guidelines add a warning that belongs here: “don’t include promotions in sales receipt messages.” A receipt subject line that turns into a sale announcement breaks that rule before the email is even opened.

Which urgent subject lines are honest

Urgency in a subject line is a claim about time, and the claim is either true or it is not. “Ends Sunday at midnight” is honest when the price changes on Sunday at midnight. “Last chance” sent every Friday for a sale that never ends is what the FTC’s 2022 staff report on dark patterns calls a “False Limited Time Message”, and the report names a fake countdown clock as a “Baseless Countdown Timer”. Fake countdown timers quotes the FTC report, EU law and the UK’s 2024 Act in full.

A simple test: could you put the deadline in a calendar invite? If you can name the moment, name it in the subject line. If you cannot, write about the offer instead of the clock.

When there is a real deadline, the subject line and the email body should agree. A countdown image inside the email shows the time left at the moment the reader opens it, while the subject line can only say what was true when you sent it.

You can make one like it in the free countdown timer generator, with no account for 500 opens, or 1,000 when you sign in. The flash sale playbook shows which send in a sale carries the timer and what each subject line says.

How long should an email subject line be?

There is no number that holds across inboxes, and any guide that gives one exact count is guessing at your reader’s screen. No major mail client publishes a fixed number of subject characters it shows in the inbox list. What is cut depends on the width of the screen, the font size the reader chose, whether a preview pane is open and how long the sender name is.

The standard that defines email, RFC 5322, describes the Subject field as “a short string identifying the topic of the message”. Its line length rule says each line “MUST be no more than 998 characters, and SHOULD be no more than 78 characters”, but that is a rule about how header lines are written, not how many characters a reader sees, because a long subject can be folded over several lines and joined again by the mail client.

So the practical rules are these:

• Put the words that carry the message in the first part of the line.
• Read your subject in a test send on a phone before you send it to the list.
• Measure your own. The example subject lines on this page run from 23 characters (“Order 48213 has shipped”) to 47 (“Your booking for Saturday, and how to change it”), counted with a script including spaces, and every one of them still makes sense if the last few words are cut.

Do subject lines affect deliverability?

A subject line is one input among many, and the mailbox providers do not publish how much it weighs. What they do publish is about the sender: authentication, complaint rates, unsubscribe links. Gmail’s and Yahoo’s pages above treat a deceptive subject line as a problem in the same breath as false headers, so a misleading subject line is something both providers name as a problem, whatever weight their filters give it. Countdown timers and deliverability covers what an image in the email does and does not change.

Questions and answers

What makes a good email subject line?

It says what is inside and why it matters to the reader today, with the important words first. It agrees with the email it opens, and if it names a deadline, the deadline is real.

Should I use emoji in email subject lines?

None of the mailbox provider guidelines quoted here forbids them. Each reader’s device draws them in its own style, so read the subject in a test send, and never let an emoji replace a word the subject needs.

Can I put “Re:” in a promotional subject line?

Not according to Gmail’s guidelines, which say not to start a subject with “Re:” or “Fwd:” unless the message really is a reply or a forward.

Is a misleading subject line illegal?

In the US, the CAN-SPAM Act covers commercial email, and the FTC’s guide says plainly not to use deceptive subject lines. This page is not legal advice; read the FTC’s guide for the full rules.

How many characters does Gmail show in a subject line?

Google does not publish a number, and the count changes with screen width, font size and sender name length. Read your own subject in a test send on a phone.

Should every sale email have a deadline in the subject line?

Only if the sale has one. A named end time is useful to a reader planning a purchase. A deadline that resets or never arrives is the pattern regulators describe as a false limited time message.