The subject line is the only part of your email most people read before deciding what to do with it. Open, skip, archive or delete: that choice happens in a second or two, usually on a phone, often while doing something else. You don’t need clever tricks to win that moment. You need a line that tells the right reader, quickly and honestly, why this email is worth their time.
Here is a practical way to write subject lines for a small list, plus a few rules you shouldn’t bend.
Start With the One Thing the Email Delivers
Before you write the subject line, finish this sentence: “After reading this email, my subscriber will be able to…” If you can’t finish it, the problem isn’t the subject line. It’s the email.
Once you have that sentence, the subject line is usually a shorter version of it. “How to price your first template” is plain, but it tells a reader exactly what’s inside. Plain and clear beats clever and vague, especially for a list that doesn’t know you well yet.
Keep It Short and Put the Important Words First
Inboxes cut off long subject lines, and phones cut them off sooner. Litmus suggests keeping subject lines to about 9 words and roughly 60 characters, and notes that mobile screens often show only about 25 to 30 characters (as of their May 2023 guidance). Exact cutoffs depend on the device and email app, so treat those numbers as a rough guide, not a rule.
The practical takeaway: put the words that matter at the front. “Your checklist: 5 steps before you launch” survives truncation better than “I wanted to share something with you about launching.”
Use the Preview Text as Your Second Line
Most email apps show a short snippet after the subject line, usually pulled from the start of your email or from a “preview text” field your email service lets you set. If you leave it empty, readers may see “View this email in your browser” or a stray image description.
Use that space to finish the thought. A subject line names the topic; the preview text adds the reason to care. For example:
- Subject: “The 20-minute email habit”
- Preview: “What to send when you have nothing new to sell”
Five Subject Line Patterns That Stay Honest
You don’t need a swipe file of hundreds of formulas. A handful of plain patterns covers most emails a solo business sends:
- The direct promise: “How to write a welcome email in 15 minutes”
- The question your reader is already asking: “Do you need an LLC before your first sale?”
- The specific number: “3 mistakes on most opt-in pages”
- The plain update: “New: the planner templates are live”
- The curiosity line that still tells the truth: “The DNS setting most small senders skip” only works if the email really names that setting
Rotate between them. Using the same pattern every week makes your emails blend together.
The Rule You Can’t Break: Don’t Mislead
In the US, the CAN-SPAM Act says the subject line of a commercial email must accurately reflect what’s in the message, and your “From” and “Reply-To” details must identify who is sending it. The Federal Trade Commission’s compliance guide also says the law makes no exception for business-to-business email, and lists penalties of up to $53,088 for each violating email (as of October 2026; the amount is adjusted for inflation). Read the FTC’s CAN-SPAM guide yourself. This is general information, not legal advice, and other countries have their own rules.
Even when a tactic is technically legal, it can still cost you trust. Fake “Re:” or “Fwd:” prefixes, false urgency (“Last chance!” when nothing is ending) and bait-and-switch topics might lift opens once, but they teach people to ignore you. A small list is built on trust, and trust is slow to rebuild.
Test Without Fooling Yourself
Many email services let you send two subject lines to part of your list and then send the winner to everyone else. Kit’s help center, for example, says a two-variant test sends each version to 15% of recipients and the winner to the remaining 70%, and it suggests at least 500 recipients for a two-way test because smaller lists may not give reliable results (as of October 2026). Kit picks the winner by open rate.
Open rates have a known weak spot. Mailchimp’s help center explains that Apple’s Mail Privacy Protection can load tracking pixels even when a subscriber hasn’t opened the email, which inflates open rates. Mailchimp suggests leaning on clicks, unsubscribes and conversions instead. For a small list, that means:
- Don’t treat a few points of difference in opens as a lesson.
- Watch clicks and replies over several sends, not one.
- Keep a simple log of subject lines and click rates so patterns show up over time.
A Quick Checklist Before You Hit Send
- Does the subject line match what the email actually delivers?
- Are the most important words in the first 30 characters or so?
- Have you written preview text instead of leaving it blank?
- Would you be comfortable if a subscriber read it out loud back to you?
- Is your name or business name clear in the “From” field?
Results vary from list to list, and there’s no subject line that guarantees opens. What works over time is boring in the best way: clear lines, honest promises and emails that deliver on them.
Do This Today
Open your last five sent emails and copy their subject lines into a note. Rewrite each one so the main benefit appears in the first 30 characters, and add a line of preview text under each. Use the strongest version on your next send.
More on Totally Relentless
- How to Write a Welcome Email That Sets the Right Expectations
- Email Segmentation Basics: Tags vs. Segments for a Small List
- SPF, DKIM and DMARC in Plain Words: Keep Your Emails Out of Spam
