How to Write Subject Lines That Get Opened
Practical formulas and examples for writing e-commerce email subject lines that cut through inbox noise and drive opens — without resorting to spam tactics.
You spent hours crafting the perfect email. Beautiful design, compelling copy, a great offer. None of it matters if nobody opens it. In e-commerce, your subject line is the gatekeeper — and the difference between a 15% and a 35% open rate can mean thousands of dollars in revenue per campaign.
Here's how to write subject lines that actually get opened.
Why Subject Lines Make or Break Campaigns
The average person receives over 100 emails per day. Your subject line competes with work messages, personal emails, and dozens of other brands. You have about 1.5 seconds to earn the open. That means every word counts.
The Two Jobs of a Subject Line
First, it must create enough curiosity or value to earn the open. Second, it must set an accurate expectation for what's inside. Clickbait subject lines might boost opens once, but they destroy trust and hurt future engagement.
Subject Line Formulas That Work for E-Commerce
The Curiosity Gap
Tease information without revealing everything. "You left something behind..." works for abandoned cart because the reader needs to open the email to see what. "The one thing customers wish they'd ordered sooner" creates intrigue without being misleading.
Urgency and Scarcity
"24 hours left: 20% off everything" and "Only 3 left in your size" create time pressure. Use genuine urgency only — fake countdown timers erode trust fast.
Personalization
Subject lines with first names or product references outperform generic ones. "Sarah, your favorites are back in stock" feels personal. "{{product_name}} is waiting in your cart" reminds them of something specific.
The Direct Benefit
Lead with what the reader gains. "Free shipping on your next order" and "Get 30% off your first purchase" are clear and compelling. Sometimes straightforward beats clever.
The Question
"Ready for your best skin yet?" and "Still thinking about that jacket?" engage the reader by prompting a mental response. Questions feel conversational, not promotional.
Social Proof
"Join 10,000+ happy customers" and "Our #1 bestseller is back" leverage the crowd effect. If everyone else loves it, it must be worth opening.
Subject Line Length: Short vs Long
Mobile displays 30–40 characters before truncating. Front-load the most important words. That said, longer subject lines (50–70 characters) can work for engaged audiences who want more context. Test both for your specific list.
Preview Text: Your Secret Second Subject Line
The preview text (preheader) appears after the subject line in most inboxes. Never leave it blank or repeat the subject. Extend the promise: Subject: "Your cart is waiting" → Preview: "Complete your order in one click + free shipping over $50."
What to Avoid
ALL CAPS and excessive punctuation: "FREE SHIPPING!!!" screams spam filter.
Misleading clickbait: "Re: Your order" when it's a marketing email destroys trust.
Overused spam triggers: "Act now," "Limited time," "Free" used excessively can hurt deliverability.
Generic subjects: "Newsletter #47" and "Monthly update" give zero reason to open.
A/B Testing Subject Lines
Test one variable at a time. Send version A and B to 20% of your list each, wait 2–4 hours, then send the winner to the remaining 60%. Test subject line length, emoji vs no emoji, personalization vs generic, question vs statement. Keep a swipe file of winners to inform future campaigns.
Seasonal and Campaign-Specific Tips
During holidays, inboxes are crowded. Stand out with specificity: "Your early Black Friday access starts now" beats "Big holiday sale!" For product launches, tease exclusivity: "First look: Spring collection drops tomorrow."
For win-back campaigns, honesty works: "We miss you — and we've got something for you" outperforms aggressive discount subject lines for many brands.
Emoji in Subject Lines: Yes or No?
Emojis can boost open rates by 10–15% for some audiences, especially younger demographics and lifestyle brands. A well-placed 🎁 or ✨ adds visual interest in a crowded inbox. But overuse looks unprofessional, and emojis render inconsistently across email clients. Test emoji vs no emoji for your specific list. One emoji max — more than that reads as spam.
Subject Lines by Email Type
Different automations call for different approaches. Welcome emails work with warm, inviting subjects. Cart recovery needs curiosity or urgency. Post-purchase emails should feel personal and service-oriented — "Your order is on its way" not "Buy more now." Win-back emails benefit from honesty and nostalgia. Match the subject line tone to the relationship stage.
Building a Subject Line Workflow
Before every send, write 5–10 subject line variations. Narrow to your top 2–3. A/B test when possible. Track open rates by subject line type over time to learn what resonates with your specific audience.
Coming up with fresh subject lines for every email in a sequence is tedious. ListCraft generates subject lines alongside full email sequences, giving you multiple options to test for welcome series, cart recovery, and promotional campaigns — so you're never staring at a blank subject line field again.
Great subject lines are concise, honest, and give the reader a reason to open right now. Master them, and everything else in your email program works harder.