The ten rules of email marketing

Ten rules carry most of what makes email work for a small business. Each rests on the law, the mailbox providers' own rules or published results, and each comes with what to do.

The short version

1. 1

   Mail only people who asked, keep proof that they did, and never buy, rent or scrape a list.

2. 2

   Welcome every new subscriber at once, with a short sequence started by the sign-up form.

3. 3

   Send on a steady rhythm: weekly by default, never less than monthly, with the busy dates on top.

4. 4

   Follow up the people who click.

5. 5

   Judge and group people by clicks, replies and purchases, never by opens.

6. 6

   Stay in the inbox: complaints under one in 1,000 emails, records that prove who you are, and leaving made easy.

7. 7

   Win back the quiet, then stop mailing the silent.

8. 8

   Measure five numbers against your own results, and on a small list, test only big differences.

9. 9

   Plan the year on one page, with a few dates, each run as a short sequence.

10. 10

    Know what a subscriber is worth before paying for one, and grow from your own traffic first.

Where to begin, in order: Where to start: your first 90 days.

1. Mail only people who asked

• Consent comes first in the EU, the UK, Canada, Australia and New Zealand. The US lets a business email without asking, but never without honesty, an address and a way out.
• The maximum penalties: up to $53,088 per email in the US; up to C$10 million per violation for a business in Canada; £17.5 million or 4% of worldwide turnover in the UK since 5 February 2026; €20 million or 4% in the EU.
• Proof is yours to keep. In Canada, New Zealand, Australia, the EU and the UK, the sender has to show consent.
• A bought or scraped list carries spam traps and people who'll complain. Spamhaus describes a recycled trap as a once-real address that a provider closed, refused mail to "often 12 months or more", then switched back on.

Do this: a form that says what's coming and how often, an unticked consent box, and a record of every consent: who, when, where, the words they saw, how, and what for. Use double opt-in for cold traffic, and for readers in the EU, the UK, Canada and New Zealand: Email marketing and the law.

2. Welcome every new subscriber at once

• GetResponse, 2023 data: welcome emails drew 83.63% opens and 16.60% clicks.
• Omnisend, 2025: welcome and abandoned-cart emails brought 76% of all orders from automated email.
• Klaviyo: sequences were 5.3% of sends and about 41% of email revenue.

Do this: four or five emails over 7 to 10 days. The promised gift at once, your story, proof (a result, a customer), a first offer, and a question that sorts people by interest. It's the most-read email you send, so it's the first one to test: Welcome, newsletter, offer and launch emails.

3. Send on a steady rhythm

• Zhang, Kumar and Cosguner (2017): the most profitable frequency averaged 7 emails a month, from 5 to 14 by customer. Sending 4 a month lost about 32% of lifetime profit; sending 10 lost about 16%. Too little cost twice what too much did.
• Google: "send email at a consistent rate", and "avoid sending email in bursts".
• Klaviyo starts lists under 20,000 at one campaign a week. Nonprofits send about 50 messages a year (M+R).

Do this: a set day, weekly, or fortnightly where you really have less to say. Count everything one person gets, campaigns and sequences together, and keep it to about one a day and four a week. Step up only when, over 8 to 12 weeks, complaints stay under 0.1% and revenue per subscriber rises: How often to send.

4. Follow up the people who click

• Omnisend, 2025: "Nearly one in three clicks on an automated email resulted in a purchase".
• Klaviyo: sequences reached a 2.11% placed-order rate, against 0.16% for campaigns.

Someone who clicked an offer and didn't act is the warmest person on your list.

Do this: every campaign with an offer gets a follow-up of two or three emails over a week, for the people who clicked and didn't act: the offer again, the main objection answered, and a real deadline. People who buy leave it: The emails a business sends.

5. Judge by clicks, replies and purchases, never opens

• Opens no longer mean reading. Since 2021, Apple's Mail Privacy Protection loads every email in the background, so an open is recorded whether anyone read it or not. Apple made 76.56% of recorded opens in September 2026, and about 55 to 60% of all opens came through its privacy setting (Litmus).
• Groups work: Mailchimp found segmented campaigns drew 100.95% more clicks and 9.37% fewer unsubscribes than unsegmented ones.

Do this: count someone as engaged by their clicks, replies and purchases. Start with three groups: customers and prospects, the engaged and the quiet, and one interest question asked at sign-up or in the welcome: The right email for the right people.

6. Stay in the inbox

• Complaints: Google says under 0.10%, and never 0.30%; Yahoo says under 0.3%. The 2025 average was 0.06% (Validity). 0.1% is one complaint per 1,000 emails, so on a send of 5,000, six complaints cross the line.
• Proof of who you are: since February 2024, Google and Yahoo have required bulk senders to have SPF, DKIM and aligned DMARC records, and a one-click unsubscribe. Google counts a sender as bulk at close to 5,000 emails a day to personal Gmail addresses. Microsoft added its own rules for senders of more than 5,000 a day in 2025.
• Leaving: an unsubscribe must be honoured within 48 hours under Google's rule, and 2 days under Yahoo's. The law allows longer: 5 business days in Australia, 5 working days in New Zealand, and 10 business days in the US and Canada.

Do this: prevent complaints at the source, with permission, a clear promise, a steady rhythm, relevance and an obvious unsubscribe. Act on every unsubscribe at once: Get into the inbox.

7. Win back the quiet, then stop

• Return Path, win-backs at 33 retailers (2014): 45% of the people who got one read a later email, on average 57 days later. An email asking people to confirm they still wanted the mail was read by only 1.8%.
• Spamhaus puts the usual window without engagement before removal at three to twelve months. Google: "consider unsubscribing recipients who don't open or read your messages".

Do this: a win-back of two or three emails over at least two months, for people with no clicks, replies or purchases in 90 to 180 days. Then stop mailing anyone who still doesn't respond: after 6 months for a weekly sender, 12 months at most for a monthly one: Carts, win-backs, events and receipts.

8. Measure five numbers against your own

• The five: click rate, the goal (orders, bookings, replies or donations), unsubscribes, complaints and net list growth. Opens never lead.
• What normal looks like: MailerLite's medians for December 2025 were a 2.09% click rate and a 0.22% unsubscribe rate. Compare each campaign with the middle of your own last ten.
• What a small list can see: against a 2% click rate, 2,500 people a version spot only a difference of 63% or more, and 250 a version only 3.6 times the clicks.

Do this: graph the five numbers weekly. Test the offer, the audience or the message, never a button colour. Split the whole send in two, repeat the test, add up the results and keep a log: Measure what matters, Test your emails.

9. Plan the year on one page

• Shops: 64% of US consumers said they'd likely wait until Thanksgiving weekend for most of their holiday shopping (NRF, October 2026).
• Nonprofits took 37% of their 2025 online revenue in December, and 4% on the last day of the year (M+R).
• The load: a weekly email plus six dates of three emails each comes to 5.5 to 6 emails a month, under Zhang's average best of 7.

Do this: write the one-page plan. Use each market's own dates: Mother's Day is 7 March 2027 in the UK, and 9 May in the US, Canada, Australia and New Zealand. Shops put the main offer on Thanksgiving weekend; nonprofits plan December first: Plan your email year.

10. Know what a subscriber is worth

• The worked example: a shop with 5,000 subscribers, four campaigns a month, a 40% margin and a list that loses 20% a year. One more subscriber is worth about $24.69 with sequences, or $17.28 from campaigns alone.
• What sign-ups cost: Facebook lead ads average $27.39 a lead (LocaliQ, September 2026), which takes about 67 months to pay back, longer than the average stay. Paid traffic to a sign-up page comes to about $9 a sign-up, paid back in about 22 months.
• Your own traffic costs only the form: pop-ups turn 2.1% of displays into sign-ups (Omnisend, 2025 data), and a focused landing page converts 6.6% of visitors at the median (Unbounce, 2024).

Do this: put a way to join everywhere people show interest: a form across the website, a pop-up after 6 to 10 seconds, the checkout box, and a page for a free guide. Work out revenue per subscriber from your own figures, pay for sign-ups only below their value, and judge paid sign-ups as their own group: Build your email list.

When to act on the numbers

Short answers

• "How often should I email?" Weekly, on a set day, and never less than monthly. Step up only while complaints stay low and revenue per subscriber rises.
• "What's a good open rate?" Opens no longer prove reading: since 2021, Apple's mail app loads email in the background, which records an open whether or not anyone reads it. Judge clicks, where about 2% is normal, and your goal, against your own usual results.
• "When's the best time to send?" A fixed weekday morning in your readers' time zone. It matters less than what's in the email. Test another time by clicks and sales, if at all.
• "Can I bring in this list?" Only if the people on it asked to hear from you, and you can show it. Never a bought, rented or scraped list.
• "Do I need double opt-in?" It gives the strongest record of consent. Use it for cold traffic, and for readers in the EU, the UK, Canada and New Zealand. A clear box at checkout is enough for customers.
• "Why did my email go to spam?" Usually reputation, not wording: complaints, bounces, people who never respond, or where the list came from. Check those first.
• "What must every email include?" Your business name, your postal address, one more way to get in touch, and a visible unsubscribe link.
• "What should I send?" Mostly useful content, with offers in the mix. One email, one job. For each group, ask what the next email is meant to make them do.
• "When do I stop emailing someone?" After a win-back of several emails over two months, if they still don't click, reply or buy.
• "Which version of my test won?" With a few hundred sends each, only a big gap means anything. Run it again.
• "Should I pay to grow my list?" Work out what a subscriber is worth first. On typical shop figures, a $27 lead takes longer to pay back than the subscriber stays.
• "Is email worth it?" The famous returns, £41 or $36 back for each 1 spent, come from surveys of marketers. Email usually pays because it costs little to send. Your own figures, as they build, are the answer.

Doing it here

• Handled for you: every email's footer, with your business name, your postal address and an unsubscribe link; the one-click unsubscribe headers; the pace of every send; and every unsubscribe, honoured on all your lists: Unsubscribes, honoured everywhere.
• Yours: your address, kept in your brand; your consent records; the lists you bring in; and what your emails say: Set up your brand.
• Every send goes out at a natural pace for each mailbox provider, so you decide how often to send, never how fast: Natural pace, and why it isn't warm-up.