Email Subject Lines and Preview Text

Before anyone reads your email, they see three things in their inbox: the sender name, the subject line and a snippet of preview text. Together these decide whether your message is opened, saved or ignored. This guide explains how to write clear, honest subject lines and preview text that respect your readers.

The three parts of an inbox first impression

Sender name

Use a consistent, recognizable sender name, usually your business name or a combination such as "Maya at Riverside Books." Changing it often confuses subscribers. Under the CAN-SPAM Act, your header information, including the "From" name, must accurately identify who sent the message.

Subject line

The subject line tells people what the email is about. The FTC's CAN-SPAM guidance states that subject lines must not be deceptive and should accurately reflect the content of the message.

Preview text

Preview text (also called preheader text) is the short line many inboxes show after the subject. If you do not set it, email programs often display the first words of your email, which might be "View in browser" or an image description. Setting it deliberately gives you a second line to add useful context.

Principles for clear subject lines

• Be specific. "Spring workshop dates are here" beats "Exciting news!"
• Lead with the benefit or topic. Put the most important words first, because long subject lines get cut off on phones.
• Match the content. If the email is mostly about a sale, do not disguise it as a personal note.
• Use your voice. A playful brand can be playful; a calm brand can be calm.
• Keep punctuation natural. Multiple exclamation points and all caps can feel shouty.

Patterns that often work

• Clear topic: "Your guide to repotting houseplants"
• Question: "Is your bike ready for winter?"
• Useful number: "5 easy weeknight dinners for busy families" (when the email actually contains five)
• Update: "New hours starting March 1"

There is no formula that guarantees opens. Different audiences respond to different styles, and results change over time.

Writing preview text that helps

Treat preview text as a supporting line. It should add information, not repeat the subject.

What to avoid

• Fake "Re:" or "Fwd:" prefixes that suggest an ongoing conversation that does not exist
• False urgency, such as "Last chance!" when nothing is ending
• Misleading personalization, such as implying a private message when it is a newsletter
• Bait-and-switch topics that promise content the email does not contain
• Spammy patterns like excessive symbols or misleading claims of winnings

These tactics might produce a brief bump in opens, but they erode trust, increase complaints and can conflict with legal requirements. Mailbox providers' sender guidelines, including Google's, also note that user complaints affect whether mail reaches the inbox.

Accessibility and emoji

Emoji can add personality but should not replace words. Screen readers read emoji descriptions aloud, so "🔥🔥🔥 Sale" may be read as "fire fire fire sale." If you use emoji, use one at most, and make sure the subject still makes sense without it.

Testing ideas carefully

Many email tools let you send two subject line versions to small portions of your list and compare results. This can be useful for larger lists, but small lists often produce differences that are too small to mean much. If you test, change only one thing at a time and treat results as learning, not proof. Our guide to simple marketing experiments explains how to keep a test log.

A quick writing process

1. Write the email first.
2. Summarize its main point in one sentence.
3. Turn that sentence into a short subject line.
4. Use preview text to add the second most useful detail.
5. Read both lines on a phone-sized screen.
6. Ask: would a subscriber feel this was accurate after reading the email?

Common mistakes

• Vague subjects like "Newsletter #14"
• Missing preview text, leaving technical snippets visible
• Different sender names from one email to the next
• Overpromising in the subject what the email cannot deliver

Frequently asked questions

Is there an ideal subject line length?

There is no universal ideal, but phones often show only the first several words. Put the most important words first and keep it as short as clarity allows.

Should I personalize subject lines with names?

Personalization can feel friendly when used sparingly and accurately. Make sure your data is correct, and never imply a private message when it is a newsletter.

Can I reuse subject lines?

Yes for recurring emails like a monthly letter, as long as each still describes the content accurately.

Subject line checklist

• My sender name is consistent and accurate
• The subject line clearly reflects the content
• Key words appear early
• Preview text adds new, useful information
• No fake urgency, fake replies or misleading claims
• The subject reads well with or without emoji
• I checked how it looks on a phone

Keep learning

Strong subject lines start with a strong list and a good first impression. Review email opt-in best practices and writing a welcome email sequence.