Most email marketing fails at the subject line. Not in the body, not in the call to action, but in the first 50 characters that decide whether the email gets opened at all.
The average open rate for business email sits between 20% and 25%. That means three quarters of your subscribers are not reading what you sent. In most cases, the subject line is the primary reason. It either earned the click or it did not.
Use the Email Subject Tester to score any subject line against best-practice criteria before you send.
85 Subject Line Templates by Type
The templates below are organised by the technique they use. Each works best in specific contexts - match the technique to your audience and goal.
Clarity (Tell Them Exactly What Is Inside)
Best for: transactional emails, cold outreach, professional B2B audiences.
| # | Template | Example |
|---|---|---|
| 1 | [Number] ways to [achieve outcome] | 3 ways to reduce your invoicing time |
| 2 | How to [do specific thing] in [timeframe] | How to write a freelance contract in 30 minutes |
| 3 | Your [resource/report/result] is ready | Your profit margin report is ready |
| 4 | [Specific benefit] for [specific audience] | Lower card fees for Shopify sellers |
| 5 | The [timeframe] guide to [topic] | The April guide to IR35 changes |
| 6 | [Number] [topic] templates you can use today | 5 invoice email templates you can use today |
| 7 | What most [audience] get wrong about [topic] | What most freelancers get wrong about day rates |
| 8 | [Outcome]: here is how we did it | 40% fewer late payments: here is how we did it |
| 9 | Your [month] [report/digest] | Your April performance digest |
| 10 | [Action] before [deadline or event] | Update your contracts before April 6 |
Curiosity (Create a Gap They Want to Close)
Best for: warm lists, re-engagement, marketing emails to audiences who trust the sender.
| # | Template | Example |
|---|---|---|
| 11 | The mistake most [audience] make with [topic] | The mistake most consultants make with proposals |
| 12 | This changes how you think about [topic] | This changes how you think about pricing |
| 13 | Have you seen this? | Have you seen this? |
| 14 | We found something in your [account/data] | We found something in your usage data |
| 15 | Nobody talks about this part of [topic] | Nobody talks about this part of client contracts |
| 16 | Why [common belief] is wrong | Why free shipping is not always free |
| 17 | [Number] things we wish we knew before [event] | 4 things we wish we knew before launching |
| 18 | Something worth reading on a [day] | Something worth reading on a Friday |
| 19 | This is not what you expect | This is not what you expect |
| 20 | Quick question | Quick question |
Urgency and Scarcity (Real Deadlines Only)
Best for: promotional emails, limited offers, event reminders. Only use when the urgency is genuine.
| # | Template | Example |
|---|---|---|
| 21 | [X] hours left to [action] | 48 hours left to lock in the early price |
| 22 | Last chance to [action] | Last chance to claim your free audit |
| 23 | Closes [day]: [offer] | Closes Friday: 30% off annual plan |
| 24 | [Number] spots left | 3 spots left for June |
| 25 | This offer expires at midnight | This offer expires at midnight |
| 26 | We are closing [thing] on [date] | We are closing the waitlist on May 1 |
| 27 | Do not miss [specific thing] | Do not miss the April rate change |
| 28 | [Event/sale] starts in [timeframe] | Summer sale starts in 3 days |
| 29 | Today only: [offer] | Today only: free setup call |
| 30 | Final reminder: [action] | Final reminder: renew before April 30 |
Personalised (Contextual Signals)
Best for: behavioural trigger emails, onboarding sequences, B2B outreach with clean data.
| # | Template | Example |
|---|---|---|
| 31 | [First name], [specific observation] | Sarah, you have not set up your invoice template yet |
| 32 | Based on what you [did], [recommendation] | Based on what you downloaded, here is the next step |
| 33 | [Company], a thought on your [topic] | Acme Ltd, a thought on your pricing page |
| 34 | You visited [page/topic] - here is more | You visited our IR35 guide - here is more |
| 35 | [Specific role], this is for you | Freelance designers, this is for you |
| 36 | Since you [action], you might want this | Since you tried the calculator, you might want this |
| 37 | [Location]-specific: [topic] | UK freelancers: what changes in April |
| 38 | Still thinking about [topic]? | Still thinking about going limited company? |
| 39 | You asked about [topic] - the answer | You asked about Stripe fees - the answer |
| 40 | [Number] days since [event] - here is what is next | 7 days since signup - here is what is next |
Cold Email (Unknown Sender to Unknown Recipient)
Best for: B2B prospecting. Clarity and relevance beat curiosity when the recipient does not know you.
| # | Template | Example |
|---|---|---|
| 41 | [Specific outcome] for [company type] | Faster invoicing for marketing agencies |
| 42 | [Mutual connection or trigger] - [context] | Saw your post about IR35 - a thought |
| 43 | Quick question about [specific thing] | Quick question about your onboarding flow |
| 44 | [Company] + [your company] | Acme + ClearCut |
| 45 | Idea for [company] | Idea for Acme Ltd |
| 46 | [Number]-word pitch for [company] | 30-word pitch for Acme Ltd |
| 47 | Is [problem] on your radar this quarter? | Is payment delays on your radar this quarter? |
| 48 | Re: [relevant recent event at their company] | Re: your new pricing page |
| 49 | [Specific result] for similar [company type] | 22% fewer disputes for similar agencies |
| 50 | Can I send you [specific useful thing]? | Can I send you our contractor onboarding checklist? |
B2B (Professional, Outcome-Focused)
Best for: SaaS, services, consultancy audiences evaluating ROI.
| # | Template | Example |
|---|---|---|
| 51 | How [company type] reduce [cost/time] by [%] | How agencies reduce invoicing time by 40% |
| 52 | The [job function] guide to [topic] | The finance manager guide to contractor IR35 |
| 53 | [Number] questions your [role] should ask about [topic] | 3 questions your CFO should ask about card fees |
| 54 | What [industry] leaders do differently with [topic] | What top agencies do differently with contracts |
| 55 | [Topic] benchmark: where does your [metric] stand? | Invoice payment benchmark: where does yours stand? |
| 56 | [Regulation/change] and what it means for [audience] | April NMW changes and what they mean for HR |
| 57 | [Process] is costing [audience] [cost/time] | Manual invoicing is costing agencies 4 hours a week |
| 58 | New data: [insight] | New data: 68% of freelancers undercharge |
| 59 | Your [process/tool] could be doing [better outcome] | Your pricing page could be doing a lot more |
| 60 | One thing holding [audience] back from [outcome] | One thing holding consultants back from better rates |
Re-engagement (Dormant Subscribers)
Best for: win-back campaigns, list cleaning, reactivation sequences.
| # | Template | Example |
|---|---|---|
| 61 | We miss you - and we have something new | We miss you - and we have something new |
| 62 | Is this still useful to you? | Is this still useful to you? |
| 63 | A lot has changed since you last visited | A lot has changed since you last visited |
| 64 | Should we keep sending these? | Should we keep sending these? |
| 65 | One last thing before we let you go | One last thing before we let you go |
| 66 | We updated [thing] - thought you should see | We updated the pricing calculator - thought you should see |
| 67 | [Number] things you missed while you were away | 6 things you missed while you were away |
| 68 | You might not know about [new feature/resource] | You might not know about the new DOCX export |
| 69 | Pick up where you left off | Pick up where you left off |
| 70 | Come back and get [specific thing] free | Come back and get your first DOCX export free |
Short and Conversational (Under 30 Characters)
Best for: warm audiences, personal tone brands, mobile-first lists.
| # | Template | Example |
|---|---|---|
| 71 | Thought of you | Thought of you |
| 72 | Quick update | Quick update |
| 73 | This is useful | This is useful |
| 74 | Worth 2 minutes | Worth 2 minutes |
| 75 | Something came up | Something came up |
| 76 | Read this today | Read this today |
| 77 | A small thing | A small thing |
| 78 | You asked, we listened | You asked, we listened |
| 79 | This worked | This worked |
| 80 | New: [one word or phrase] | New: rate calculator |
Question Openers
Best for: all audiences - questions naturally invite engagement.
| # | Template | Example |
|---|---|---|
| 81 | Are you [doing suboptimal thing]? | Are you still chasing invoices manually? |
| 82 | What would [positive outcome] mean for you? | What would getting paid on time mean for you? |
| 83 | Have you tried [approach] yet? | Have you tried the new day rate calculator yet? |
| 84 | Is [problem] slowing you down? | Is manual invoicing slowing you down? |
| 85 | What does your [metric] say about [topic]? | What does your profit margin say about your pricing? |
The Rules Behind What Works
Length
41 to 50 characters performs best on mobile, which accounts for more than half of email opens. Short (under 30 characters) works for high-trust senders using a personal tone. Long subject lines are not automatically bad, but your most compelling phrase must appear within the first 50 characters - mobile truncates everything after that.
Curiosity vs Clarity
Clarity works for cold audiences and transactional emails. The reader does not trust you yet and needs to know what they are getting before they open.
Curiosity works for warm lists where the recipient already trusts the sender. Use it as a contrast to clarity, not as a default mode. If every email is a mystery, readers learn to treat them as optional.
Spam Triggers to Avoid
Words and patterns that damage deliverability: Free, Guarantee, Limited time offer, Act now, Earn money, Click here, multiple exclamation marks, ALL CAPS, manufactured urgency applied to every email.
Preview Text
Set it deliberately. The default auto-populated preview text ("View in browser", "Having trouble?") wastes the only second piece of information a recipient sees before opening. Write preview text that extends the subject line, not repeats it.
Example pair:
- Subject: "3 contract clauses that protect freelancers from late payment"
- Preview: "The third one recovered £3,800 in a real dispute."
Testing
Test one variable at a time: length, style (curiosity vs clarity), personalisation, specificity, question vs statement. Measure open rate first, then click rate and unsubscribe rate. A test on 200 recipients gives directional data; 2,000 gives statistical confidence.
Use the Email Subject Tester to check any subject line for spam risk, character count, and structural issues before it goes live.
Frequently Asked Questions
What is the best length for an email subject line? 41 to 50 characters for most audiences. Short enough to display fully on mobile; long enough to say something meaningful.
What words should I avoid? Free, Guarantee, Act now, Limited time offer, and excessive exclamation marks are the most consistent spam triggers. Beyond specific words, avoid manufactured urgency and misleading subject lines - recipients who feel tricked unsubscribe faster.
Does personalisation help? Yes, though first-name personalisation has diminishing returns as it has become standard practice. Contextual personalisation (referencing behaviour, role, or location) outperforms it. Behavioural triggers (based on a specific action) outperform both.
How do I test subject lines? A/B test one variable at a time with at least 200 recipients per variant. Test curiosity vs clarity, long vs short, personalised vs generic. Use the Email Subject Tester for a pre-send structural check.
Related reading: How to Write a Professional Email Signature