Email Marketing Strategy: Permission, Deliverability and Emails That Earn

An email marketing strategy is a plan for building a list of people who want to hear from you, sending them useful messages at the right moments, keeping your emails out of the spam folder and measuring results by revenue, not just opens. It rests on three things: permission, deliverability and relevance. Get those right and email is one of the most reliable channels you own.

Email is a channel you control. Unlike search rankings or social reach, nobody can change an algorithm and take your list away. But email has strict rules, in law and in how mailbox providers treat senders, and since 2024 those rules have tightened. This guide covers how to build a list properly, which emails to send, how to meet the sender requirements of Gmail, how to write and design for results, how to test, how to measure and what to avoid. For automation, see our guide to marketing automation with AI. For the wider plan, see our digital marketing strategy guide.

Why email still works

• You own the list. You reach people directly, without a platform deciding who sees you.
• People opted in. A subscriber has already shown interest, which usually means higher intent than a cold audience.
• It suits the whole journey. Welcome, nurture, purchase follow-up, retention and win-back.
• It is measurable. You can tie sends to clicks, orders and revenue.
• It is relatively cheap per message compared with paid media, once the list exists.

The caveat: it only works when people want your emails and mailbox providers trust you.

Permission and the law

United Kingdom

The ICO's guidance on electronic mail marketing says you must not send marketing emails or texts to individuals without specific consent, with a limited exception. The "soft opt-in" lets you email your own previous customers about similar products or services without fresh consent, but only if you obtained their details while selling or negotiating a sale, you gave them a clear chance to opt out when you collected their details, and you give them a chance to opt out in every message. The ICO notes that it does not apply to prospects or contacts from bought-in lists. Business-to-business rules differ for some corporate subscribers, so check the ICO's business-to-business guidance.

India

India's Digital Personal Data Protection Act, 2023 and the Rules notified in November 2025 require clear, standalone consent notices with an itemised list of the personal data collected and the specific purpose, and give people ways to withdraw consent. The Rules provide a phased compliance period. If you email people in India, review your sign-up forms and notices.

Practical rules

• Never buy or rent lists. They breach consent rules and wreck deliverability.
• Make the sign-up purpose clear: say what they will receive and how often.
• Keep records of when and how each person consented.
• Honour unsubscribes promptly.
• Include your business identity and contact details.

This is general information, not legal advice. Take advice for your own situation.

Deliverability: the technical basics

Deliverability means your emails reach the inbox instead of spam. Google's email sender guidelines set requirements for anyone sending to personal Gmail accounts, effective from 1 February 2024.

Requirement	Applies to	What it means
SPF or DKIM authentication	All senders	Prove your emails come from you. Set up at least one, ideally both
Valid DNS records and TLS	All senders	Correct forward and reverse DNS, and a secure connection
Spam rate below 0.3 percent	All senders	Measured in Google Postmaster Tools. Keep it low
Standard message format	All senders	Follow the Internet Message Format standard and do not impersonate Gmail From addresses
SPF, DKIM and DMARC	Senders of 5,000 or more messages per day to Gmail	All three, with From domain alignment. A DMARC policy of none is acceptable
One-click unsubscribe	Bulk senders, for marketing and subscribed messages	Support one-click unsubscribe, plus a visible unsubscribe link in the message body

Source: Google, Email sender guidelines. Other mailbox providers have similar expectations, and guidelines change, so check current documentation.

Practical steps to protect deliverability:

1. Send from your own domain, not a free mailbox, and authenticate it.
2. Use a reputable sending platform.
3. Warm up gradually when starting or changing platforms.
4. Clean your list. Remove hard bounces and long-term non-openers after a re-permission attempt.
5. Keep complaints low. Send only what people expect, and make unsubscribing easy, because hidden unsubscribe links cause complaints.
6. Monitor Postmaster Tools and your platform's reports.

Building your list properly

• Offer something worth signing up for. A useful guide, a template, early access, a genuine discount, or simply a good newsletter.
• Ask at the right moments. On helpful content, at checkout, after a purchase, at events and in customer conversations.
• Keep forms short. An email address and, if useful, one preference question.
• Set expectations. What they will get and how often.
• Consider double opt-in where list quality or fraud is a concern. It reduces typos and fake sign-ups at the cost of some friction.
• Collect preferences. A simple choice of topics or frequency improves relevance and reduces unsubscribes.

The emails every business should consider

Email	Purpose	Timing
Welcome series	Introduce you, set expectations, deliver the promised item, show your best content	Immediately, then over one to two weeks
Nurture or education	Answer common questions and build trust	Weekly or fortnightly
Transactional	Confirm orders, bookings and account actions. Required by customers, not promotional	Triggered
Abandoned basket or enquiry follow-up	Help people who stopped partway	Within hours, then a day or two later
Post-purchase	Onboard, ask for feedback, suggest related items	Days after purchase
Review request	Collect honest reviews	After the customer has used the product or service
Newsletter	Regular useful updates and news	Fixed rhythm you can keep
Win-back	Re-engage lapsed customers or subscribers	After a quiet period
Renewal or reminder	Prompt for renewals or repeat purchases	Ahead of the due date

Start with a welcome series and one or two triggered flows. They usually earn more per email than campaigns, because they respond to a person's actions.

Writing emails that get read and acted on

Subject line and preview text

Be clear and honest about what is inside. Short, specific subject lines tend to work well. Avoid misleading claims, false urgency and deceptive "Re:" tricks. Use the preview text to add information.

One goal per email

Decide the single action you want, such as reading an article, booking a call or buying an item, and make it obvious.

Lead with value

Put the most useful or relevant point first. Many readers decide in seconds.

Write like a person

Use plain language, a real sender name and a reply-to address that works. Short paragraphs. Descriptive link text. A single clear button.

Design for mobile

Most emails are read on phones. Use a single column, readable font sizes, generous tap targets and images with alt text, since many clients block images by default.

Always include

• A clear sender identity and a physical or registered address where required.
• A visible unsubscribe link, and a one-click method for bulk marketing sends.
• A reason the recipient is receiving the email.

Segmentation and personalisation

Relevance reduces unsubscribes and raises results. Start with simple segments based on information people gave you or actions they took.

• New subscribers versus customers.
• Interest or topic preference.
• Purchase history and recency.
• Engagement level: active, quiet, inactive.
• Location or language where it affects the offer.

Test any personalisation against a control. See our guide to AI personalisation.

Using AI in email

AI can help draft subject line variants, summarise long content into email copy, suggest send times and spot patterns in engagement. Keep human review on anything customer-facing, never paste personal data into tools you have not vetted, and remember that consent and unsubscribe rules still apply to automated sends. Use AI to speed up, not to generate volume for its own sake.

Testing

1. Test one thing at a time: subject line, send time, offer, button text or layout.
2. Use enough recipients for the result to mean something. Small lists give noisy results.
3. Judge by the goal, such as clicks or revenue, not opens alone.
4. Record and reuse what you learn.

Note that open rates have become less reliable, because some mail apps pre-load images and hide real behaviour. Rely on clicks, conversions and revenue as the main measures.

Measuring email marketing

Metric	Meaning	Caution
Delivery rate	Share of sends accepted by receiving servers	Does not tell you about inbox versus spam
Click rate	Share of recipients who clicked	A better engagement signal than opens
Conversion rate	Share who took the intended action	Needs tracking set up properly
Revenue per email or recipient	Money earned for each send	The most useful commercial measure
Unsubscribe rate	Share who opted out	A rise signals relevance or frequency problems
Spam complaint rate	Share who marked as spam	Keep very low. Google asks senders to stay below 0.3 percent
List growth and health	New sign-ups minus unsubscribes and bounces	Quality matters more than size

A 90-day plan

Period	Focus
Days 1 to 30	Authenticate your domain, choose a platform, build clear sign-up forms, write a welcome series of three to five emails
Days 31 to 60	Launch the welcome series, add a basket or enquiry follow-up, start a regular newsletter, set up reporting
Days 61 to 90	Segment by interest and engagement, run two tests, clean the list and add a win-back email

Common mistakes

• Buying or scraping lists.
• Sending without authentication or from a free mailbox address.
• Hiding the unsubscribe link.
• Sending too much or too little, with no rhythm.
• Treating every subscriber the same.
• Judging success by opens alone.
• Long, image-only emails that fail on mobile.
• Ignoring replies.
• Forgetting that consent must be recorded and honoured.

A worked example: a four-email welcome series

This is an invented example. A Bristol online shop sells loose-leaf tea. New subscribers sign up through a form that explains: "Brewing tips and new blends, about twice a month. Unsubscribe any time." The shop builds a welcome series.

Email	When	Goal	Content
1. Welcome	Immediately	Confirm and deliver the promised item	Thanks, the brewing guide, what to expect and how often. A reply invitation: "Tell us your favourite tea."
2. Story and trust	Day 3	Build familiarity	Who the founders are, how teas are sourced, a short photo story. One link to the best-selling blends
3. Help choosing	Day 7	Help new customers decide	A simple "Which tea is right for you?" guide with three recommendations. Honest note on shipping and returns
4. First order nudge	Day 12	Convert interest	A small, genuine first-order offer with a clear end date, a customer review and a link to the sampler set

The shop sends every email from a real person's name, with a working reply address and an unsubscribe link at the bottom. It records which sign-up form each person used and what they clicked, so later emails can be more relevant. After 90 days, it compares the series with its previous single welcome email by revenue per subscriber, unsubscribe rate and spam complaints, and keeps what works.

Email authentication in plain steps

If you send email from your own domain, ask whoever manages your domain and email platform to confirm each of these. The wording may differ by provider.

1. SPF. A DNS record listing the servers allowed to send email for your domain. Your sending platform will usually provide the value to add.
2. DKIM. A DNS record that lets receivers verify messages were signed by your domain. Again, your platform provides the details.
3. DMARC. A DNS record that tells receivers what to do with messages that fail checks and sends you reports. Start with a monitoring policy, review the reports, then move to stricter policies when you are confident.
4. Alignment. The domain in the visible From address should match the domain authenticated by SPF or DKIM, as Google's sender guidelines require for bulk senders.
5. Reverse DNS and TLS. Usually handled by reputable sending platforms.
6. Test. Send a test message and check the headers show SPF and DKIM passing, and use Google's Postmaster Tools to monitor spam rate if you send to Gmail users in volume.

Do not guess at DNS changes. A mistake can stop your email, so make changes carefully, or ask a specialist.

What to do when deliverability drops

Symptom	Possible causes	Actions
Emails land in spam	Authentication errors, high complaints, spammy content, a sudden volume jump	Check authentication, review recent sends, reduce volume, send only to engaged subscribers for a while
Rising spam complaints	Irrelevant or too frequent messages, hidden unsubscribe	Make unsubscribe easy, segment better, reduce frequency
High bounces	Old or bought addresses, typos at sign-up	Clean the list, add address validation, consider double opt-in
Sudden fall in clicks	Reputation problem, design or link issue, or seasonal change	Check inbox placement, test links and compare against previous patterns
Blocked by a mailbox provider	Reputation, blocklist or policy breach	Check postmaster tools and the provider's guidance, fix the cause, then request a review where possible

Subject line and preview examples

Weak	Better	Why
Newsletter October	Three autumn teas to try this week	Specific and useful
Don't miss out!!!	Our sampler set is back until Sunday	Honest, with a real date
Re: your order	Your order has shipped, and here is how to brew it	Not deceptive, and adds value
URGENT	Last orders for Christmas delivery are on 18 December	True urgency with a reason

Email and other messaging channels

Many businesses use messaging apps alongside email. The same principles apply: get clear consent, say what you will send, keep it useful and honour opt-outs. WhatsApp business messaging has its own platform rules about opt-in and message types. Do not add people to messaging lists from your email list without proper consent. See our WhatsApp marketing service for how we handle this.

Common questions about email marketing

Question	Answer
How big does my list need to be?	Quality matters more than size. A small list of interested people can outperform a large, unengaged one
Should I use plain text or designed emails?	Test both. Simple, personal-looking emails often do well, while product-led shops may benefit from images
What time should I send?	Test. Send-time tools can help, but content and relevance matter more
What do I do with inactive subscribers?	Run a re-engagement series, then remove those who do not respond, which improves deliverability
Can I email people who gave me a business card?	Rules differ. In the UK, corporate subscribers are treated differently from individuals, and you still need to identify yourself and offer an opt-out. Check the ICO's business-to-business guidance
How do I handle replies?	Monitor the reply address, and respond. Replies help engagement and show real people are behind the emails

A reliable newsletter structure

1. Subject line that promises one clear benefit.
2. Opening paragraph that gets to the point quickly.
3. One main piece of value: a tip, story, guide or offer.
4. Two or three short items of secondary interest, clearly separated.
5. One clear call to action with a descriptive button.
6. A human sign-off and a way to reply.
7. Footer with your identity, address where required, preferences and a visible unsubscribe link.

Email accessibility checklist

• Use real text for important content, not images of text.
• Add alt text to images.
• Use sufficient colour contrast and readable font sizes.
• Make links descriptive, not "click here".
• Use a logical heading and reading order.
• Keep layouts simple, so they work in screen readers and with images turned off.

A story of fixing a deliverability problem

This is an invented composite. A subscription box company in Nottingham noticed that its monthly campaign, which usually earned a healthy number of orders, produced about half as many as normal. Open rates, as reported, had not changed much, but clicks and orders were down. The marketing manager suspected a deliverability problem and began investigating.

First, she checked the basics. She sent a test to several personal inboxes and found that the message landed in the promotions tab at one provider and spam at another. She used the postmaster tools provided by the mailbox provider to look at the domain's reputation and spam rate, which had risen to a level close to the limit Google recommends staying under. She then checked the email authentication records and found that SPF and DKIM were set up correctly, but that the company had added a second sending service for transactional messages without updating its SPF record, and that DMARC was not set up at all.

Next, she looked at the list. The company had grown quickly through a competition, and about a fifth of the list had never opened or clicked an email. Some of the competition entrants may have signed up only for the prize, and some addresses looked mistyped. The company had also recently begun sending twice a week instead of once, without telling subscribers.

The plan to fix it had five parts. She updated the DNS records so that both sending services were authorised, and added a DMARC record with a monitoring policy to see reports before tightening. She paused the twice-weekly schedule and returned to a weekly rhythm. She ran a re-engagement campaign to the inactive fifth, with a clear message: "Do you still want to hear from us? Click here to stay." Those who did not respond after two attempts were removed. She added a double opt-in step for new sign-ups from competitions. And she made the unsubscribe link more visible, because she realised that some subscribers were marking messages as spam when they could not find it.

Over the next two months, the spam rate fell, inbox placement improved and clicks and orders recovered, though not to the earlier peak, because the list was smaller. Revenue per email, the measure the manager now watched most closely, was higher than before. The experience taught the company that list size is a vanity metric, that deliverability is a shared responsibility between marketing and whoever manages the company's domain, and that a change that looks small, such as sending more often, can have large effects. It now reviews its postmaster data monthly and documents any change to its sending setup.

Where we can help

We are a digital marketing agency in Manchester, UK and Mumbai, India. We set up compliant sign-up flows, authentication and automated journeys, and report on revenue. Our WhatsApp marketing and content marketing services work alongside email. Contact us for a review of your current setup.