Originally published: 4 July 2024
Last updated: May 2026
If you want to know how to improve email deliverability, the good news is that most problems can be fixed with a few practical changes. Better deliverability means more of your emails land in the inbox instead of the spam folder or promotions tab. That leads to more opens, more clicks, more enquiries and better return from your email marketing.
For UK businesses, email is still one of the most cost-effective ways to stay in touch with prospects and customers. But even strong campaigns can underperform if your emails are not reaching the right place. You might have a good offer, a well-written message and a solid list, yet still see weak results because mailbox providers do not fully trust your sending setup or your audience is no longer engaged.
This guide explains how to improve email deliverability in a practical, business-focused way. It covers the technical basics, list quality, content choices and the ongoing checks that help you improve inbox placement over time.
What Email Deliverability Means and Why It Matters
Email deliverability is the ability of your emails to reach subscribers’ inboxes successfully. It is different from delivery rate alone. A message can be marked as delivered by your platform but still end up in spam, promotions or another filtered folder where it gets ignored.
Deliverability depends on a mix of factors. These include your sender reputation, your domain setup, your list quality, your content and how people interact with your emails. Mailbox providers such as Gmail, Outlook and Yahoo use these signals to decide whether your messages deserve inbox placement.
If your deliverability is poor, every part of your email marketing becomes less effective. Your open rates drop, click rates fall and conversions suffer. You may think your campaign needs a better design or a stronger offer when the real issue is that too many emails are not being seen.
For businesses that rely on email for lead nurturing, repeat sales, appointment reminders or customer retention, this matters a great deal. Improving deliverability is not just a technical task. It is a direct way to improve marketing performance.
How inbox placement affects opens, clicks and conversions
Inbox placement has a clear impact on results. If your email lands in the main inbox, it has a much better chance of being opened and acted on. If it lands in spam, it is unlikely to be seen at all. Even if it lands in promotions, visibility can be lower depending on the subscriber’s habits.
This creates a chain reaction. Better inbox placement usually leads to:
- Higher open rates because more people actually see the email
- Higher click rates because engaged readers are more likely to take action
- More conversions because your message reaches the right audience at the right time
- Stronger sender reputation because positive engagement signals build trust
Poor inbox placement creates the opposite effect. Fewer opens and clicks tell mailbox providers that your emails may not be wanted, which can make future campaigns even harder to deliver well.
For example, if a UK service business sends a monthly email newsletter to 5,000 contacts and 20 per cent of those emails start landing in spam, that is 1,000 fewer opportunities to generate traffic, enquiries or bookings. Over time, that can become a serious commercial issue.
Common reasons emails end up in spam or promotions
There is rarely one single reason for poor deliverability. More often, it is a combination of issues. Common causes include:
- Missing or incorrect email authentication records such as SPF, DKIM and DMARC
- A weak sender reputation caused by low engagement, spam complaints or high bounce rates
- Sending to old, inactive or purchased lists
- Using misleading subject lines or spam-heavy wording
- Including too many links, too many images or poor formatting
- Sudden spikes in sending volume from a domain that has not been warmed up properly
- Low engagement over time, which signals that subscribers are not interested
- Inconsistent sending patterns that make your activity look suspicious
The promotions tab is not the same as spam, but many of the same content and formatting signals can influence where your email appears. Highly promotional language, image-heavy layouts and multiple sales links can all increase the chance of being filtered away from the main inbox.
Set Up the Technical Foundations Correctly
If you are serious about learning how to improve email deliverability, start with the technical foundations. These settings help prove that your emails are legitimate and that your domain can be trusted.
Without proper setup, even well-written campaigns sent to a good list can struggle. The technical side does not need to be overwhelming, but it does need to be correct.
Why SPF, DKIM and DMARC matter for sender trust
SPF, DKIM and DMARC are core parts of email authentication. They tell receiving servers that your emails are genuinely coming from your domain and have not been tampered with.
SPF stands for Sender Policy Framework. It lists which mail servers are allowed to send emails on behalf of your domain. If your email platform is not included in your SPF record, mailbox providers may treat your messages with suspicion.
DKIM stands for DomainKeys Identified Mail. It adds a digital signature to your emails so receiving servers can verify that the message has not been altered in transit. This supports trust and helps protect your brand.
DMARC stands for Domain-based Message Authentication, Reporting and Conformance. It builds on SPF and DKIM by telling mailbox providers what to do if an email fails authentication checks. It also gives you reporting, which can help you spot misuse of your domain.
Together, these records improve sender trust. They reduce the risk of spoofing and phishing, and they make it easier for mailbox providers to recognise your emails as legitimate.
For many businesses, these records are either missing, incomplete or set up incorrectly. That can quietly damage deliverability for months. If you are unsure, ask your web developer, IT provider or marketing partner to review your DNS settings and confirm that your email platform is properly authenticated.
How domain reputation and authentication work together
Authentication is essential, but it is only part of the picture. Your domain reputation also matters. This is the overall trust score that mailbox providers associate with your sending domain based on your behaviour over time.
A strong domain reputation is built through:
- Consistent sending patterns
- Low bounce rates
- Low spam complaint rates
- Good engagement from recipients
- Proper authentication
- Relevant content
A weak domain reputation can develop if you send to poor-quality lists, generate complaints, or send large volumes with little engagement. Once reputation drops, inbox placement becomes harder.
Think of authentication as proving your identity, while domain reputation reflects your track record. You need both. A properly authenticated domain with poor sending habits can still end up in spam. Equally, good content sent from an unauthenticated domain may not be trusted.
If you are changing email platforms or starting to send larger campaign volumes, take care not to damage your reputation. Warm up your domain gradually, send first to your most engaged subscribers and monitor results closely.
Clean and Segment Your Email List
List quality is one of the biggest factors in email deliverability. A smaller, healthier list will usually outperform a larger list full of inactive or poor-quality contacts.
Many businesses focus too much on list size and not enough on list condition. But mailbox providers care about how recipients respond. If too many people ignore, delete or complain about your emails, your sender reputation suffers.
How to remove inactive contacts and reduce bounce rates
List hygiene means keeping your database clean, accurate and engaged. This is one of the most effective email deliverability tips because it improves both technical performance and audience response.
Start by identifying contacts who have not opened or clicked your emails for a long time. The exact timeframe depends on your sales cycle, but many businesses review inactivity at 90, 180 or 365 days.
You can then:
- Run a re-engagement campaign to ask whether they still want to hear from you
- Remove or suppress contacts who remain inactive
- Delete invalid or duplicate email addresses
- Use double opt-in for new subscribers where appropriate
- Avoid purchased lists entirely
High bounce rates are a warning sign. Hard bounces usually mean the address is invalid and should be removed immediately. Soft bounces may be temporary, but repeated soft bounces should also be reviewed.
Cleaning your list helps improve inbox placement because it reduces negative signals. It also saves money if your email platform charges based on contact volume.
For example, if a retailer has 12,000 subscribers but 3,000 have not engaged in over a year, continuing to email them can drag down campaign performance. Removing or suppressing those contacts may reduce list size, but it often improves open rates, click rates and deliverability overall.
Why segmentation improves engagement and deliverability
Segmentation means dividing your list into smaller groups based on relevant criteria such as interests, purchase history, location, behaviour or stage in the buying journey.
This matters because relevance drives engagement. And engagement helps deliverability.
If you send the same generic message to everyone, many recipients will ignore it. If you send more targeted emails, people are more likely to open, click and respond. Those positive signals tell mailbox providers that your emails are wanted.
Useful segmentation ideas for UK businesses include:
- New leads versus existing customers
- Past purchasers versus non-buyers
- Service interest categories
- Geographic regions
- High-engagement subscribers versus low-engagement subscribers
- Event attendees or webinar sign-ups
You do not need a highly complex setup to see benefits. Even basic segmentation can improve results. A local B2B company, for instance, might send one email series to new enquiries and another to existing clients. That simple split can lead to stronger engagement and fewer unsubscribes.
Segmentation also supports better timing and frequency. Some groups may welcome weekly updates, while others only need monthly contact. Matching your approach to audience expectations reduces the risk of fatigue and spam complaints.
Write Emails That Encourage Engagement
Content plays a major role in deliverability. Mailbox providers look at how people interact with your emails, and your content influences those interactions.
The goal is not to game filters. It is to send useful, relevant emails that people want to open and read. That is one of the most sustainable ways to improve inbox placement.
Subject lines, preview text and content that avoid spam triggers
Subject lines are often the first thing recipients see, so they have a direct impact on opens. Poor subject lines can reduce engagement and make your emails look untrustworthy.
Good subject lines are:
- Clear
- Relevant
- Specific
- Honest
Matched to the content of the email
Avoid exaggerated claims, misleading urgency and spam-heavy language. Phrases like “Act now”, “Guaranteed income”, “Free money” or excessive use of capitals and punctuation can raise red flags. One exclamation mark may be fine. Five usually are not.
Preview text matters too. It should support the subject line and give a genuine reason to open. If your preview text is missing or poorly formatted, you lose a valuable opportunity to improve engagement.
Inside the email, focus on clarity and value. Write for real people, not algorithms. Keep your message easy to scan, with a clear purpose and a clear call to action.
Useful content approaches include:
- Sharing practical advice
- Highlighting a relevant offer
- Providing updates customers actually care about
- Answering common questions
- Linking to helpful resources
If every email is a hard sell, engagement may decline. A better approach is to balance promotional messages with genuinely useful content that builds trust.
How to balance images, links and plain text for better results
Email design affects both user experience and deliverability. Over-designed emails with too many images and links can look overly promotional and may be filtered more aggressively.
A balanced email usually performs better. That means:
- Using a sensible amount of text
- Including images that support the message rather than replace it
- Avoiding image-only emails
- Keeping the number of links reasonable
- Making sure the email is mobile-friendly
- Including a plain text version
Image-only emails are a common mistake. Some businesses create a beautiful graphic and send it as the whole message. The problem is that mailbox providers and accessibility tools cannot always interpret it properly, and recipients may not load images by default.
Too many links can also be an issue, especially if they point to different domains or use URL shorteners. Keep your links focused and relevant. If you want one main action, make that obvious rather than surrounding it with distractions.
Formatting matters as well. Use a recognisable sender name, a legitimate reply-to address and a clear footer with your business details and unsubscribe link. These are basic email marketing best practices, but they also support trust.
If your campaigns regularly land in the email spam folder, review your templates. Strip back anything unnecessary and test simpler versions. In many cases, cleaner emails perform better.
Monitor Performance and Improve Over Time
Deliverability is not something you fix once and forget. Mailbox provider standards change, audience behaviour changes and your own sending patterns evolve. Ongoing monitoring helps you spot issues early and improve steadily.
If you want to know how to improve email deliverability long term, this is where consistency matters most.
Key deliverability metrics to track in your email platform
Most email platforms provide useful data, but many businesses only look at opens and clicks. Those are important, but they are not the full picture.
Key metrics to monitor include:
- Delivery rate
- Bounce rate
- Hard bounces and soft bounces
- Open rate
- Click-through rate
- Click-to-open rate
- Unsubscribe rate
- Spam complaint rate
- Conversion rate
- List growth rate
- Engagement by segment
Watch for trends rather than isolated numbers. A single campaign may underperform for many reasons, but a pattern of rising bounces or falling opens may point to a deliverability issue.
Spam complaints deserve particular attention. Even a small number can damage sender reputation if your volume is low. Make it easy for people to unsubscribe rather than forcing them to mark your emails as spam.
It is also useful to compare performance across segments and campaign types. If one audience consistently engages well and another does not, that tells you where to focus your improvements.
For businesses sending regular campaigns, a monthly review is a sensible minimum. For higher-volume senders, weekly checks may be more appropriate.
When to review your strategy or get expert support
Sometimes small adjustments are enough. At other times, poor deliverability points to a wider strategy issue. If your emails are consistently underperforming despite good offers and decent content, it may be time to review the bigger picture.
You should consider a deeper review if:
- Open rates have dropped sharply without a clear reason
- Spam complaints are rising
- Bounce rates are consistently high
- A new platform migration has affected performance
- Your domain authentication is unclear or incomplete
- You are sending more frequently but seeing weaker results
- Your list has grown quickly and quality may have slipped
Expert support can help you identify what is really going on. That may include technical checks, list audits, content reviews, segmentation planning and campaign strategy.
If you want a wider strategy that supports email performance, lead generation and campaign planning, explore our Marketing Packages for a joined-up approach: https://stevewelshmarketing.com/services/marketing-packages/
This kind of joined-up support is often what turns email from a frustrating channel into a reliable source of leads and sales. Deliverability improves fastest when the technical setup, content, audience targeting and wider marketing plan all work together.
Improving email deliverability is not about chasing tricks. It is about building trust with mailbox providers and with your audience. When you send relevant emails from a properly configured domain to an engaged list, better inbox placement usually follows.
To recap, the most effective ways to improve email deliverability are to:
- Set up SPF, DKIM and DMARC correctly
- Protect and build your domain reputation
- Clean your list regularly
- Remove inactive and invalid contacts
- Segment your audience for relevance
- Write clear, useful emails that encourage engagement
- Avoid spam-heavy formatting and language
- Monitor key metrics and act on warning signs
- Review your wider strategy when results stall
These steps are practical, commercially useful and achievable for most businesses. You do not need to become deeply technical, but you do need to be consistent.
If your email campaigns are not reaching enough inboxes, now is the time to fix it. Steve Welsh Marketing can help you improve performance with a smarter, more joined-up approach to email and digital marketing. Get in touch to discuss your goals and build a strategy that delivers better results.
