Email deliverability best practices matter more than ever. Gmail and Yahoo now expect stronger authentication from bulk senders, and newsletter teams that ignore the basics are more likely to land in spam. If your open rates are dropping, your list quality may be part of the problem.
Read to the end for a real example of how Refact improved The Hustle’s email deliverability by cleaning a bot-filled subscriber list after a surge of fake signups.
Email Deliverability Is More Important Than You Think
You can write a strong newsletter, build a solid list, and still miss the inbox. That is what makes deliverability so frustrating. The message may be sent, but that does not mean it will be seen.
Email deliverability is the rate at which your emails reach the inbox instead of the spam folder, promotions tab, or a blocked state. For publishers, creators, and newsletter operators, it affects opens, clicks, growth, and revenue.
It also shapes how your email program performs over time. A weak setup can hurt engagement for months. A healthy setup gives you a stronger base for growth, especially when you treat your newsletter as a product instead of a one-off campaign.
7 Factors That Impact Email Deliverability
If you want better inbox placement, start with the factors email providers actually care about. These seven areas have the biggest impact.
1. Sender Reputation
Your sender reputation is your trust score. Email providers look at your domain, sending history, complaint rate, bounce rate, and engagement patterns. If too many people ignore your emails or mark them as spam, your reputation drops.
A poor sender reputation can hurt even good campaigns. A strong one makes it easier to reach the inbox consistently.
2. Content Quality
Email providers scan your content for warning signs. Misleading subject lines, too many links, heavy promotional language, and weak formatting can all raise risk.
Clear copy works better. Keep subject lines honest. Match the email to what the subscriber expected when they signed up.
3. Email List Health
List quality matters more than list size. Sending to inactive, fake, or invalid addresses tells providers your list is not well managed.
Regular list cleaning helps protect your domain. Remove hard bounces, suppress long-term inactive users, and never buy email lists.
4. Authentication Protocols
SPF, DKIM, and DMARC help prove that your emails are really coming from your domain. Without them, your messages are easier to flag or reject.
In 2024, this is not optional for serious senders. It is part of the basic setup for bulk email.
5. Subscriber Engagement
Providers pay attention to how people react to your emails. Opens, clicks, replies, saves, and forwards are positive signs. Deletions without reading and spam complaints are negative ones.
This is one reason welcome flows, onboarding, and smart follow-up sequences matter. Good email automation for newsletters can improve engagement without increasing send volume blindly.
6. Sending Frequency and Volume
Consistency builds trust. Large spikes in volume, random gaps in sending, or sudden changes in cadence can trigger filters.
If you move to a new sending domain or dedicated IP, warm it up slowly. Build volume in stages instead of sending everything at once.
7. Platform and Infrastructure Choices
Your email service provider, domain setup, signup flows, and backend systems all play a role. Bad form protection can let bots in. Weak syncs between your site and ESP can create list issues. A rushed platform change can damage deliverability fast.
If you are switching tools, proper ESP migration support can help protect list data, automations, and sender reputation during the move.
Email Content and Design Best Practices
Strong deliverability starts before the email is sent. Your content and layout affect whether people engage, ignore, or complain.
- Write for the subscriber. Keep content useful, specific, and easy to scan.
- Avoid spam signals. Do not overload the email with links, images, or hype-heavy copy.
- Personalize where it helps. Use known subscriber data to make the message more relevant.
- Design for mobile. Many readers open on phones first, so your layout needs to hold up there.
- Use one clear CTA. Too many choices can lower clicks and confuse readers.
- Test often. Review subject lines, send times, layouts, and calls to action.
For publisher brands, deliverability is tied to the full user experience, not just the email itself. Signup flows, landing pages, archives, and subscriber onboarding all affect what happens next. That is why many teams pair email work with stronger web development for publishers.
Shared IP vs Dedicated IP
The right IP setup depends on your volume, resources, and need for control.
| Option | Best for | Benefits | Tradeoffs |
|---|---|---|---|
| Shared IP | Small to mid-size senders | Lower effort, provider-managed reputation, easier start | Other senders can affect your results |
| Dedicated IP | High-volume senders | More control over reputation and sending patterns | Needs careful warm-up and ongoing management |
If you do not have the time or team to manage reputation closely, a good shared setup may be safer. If you send large volumes and need control, a dedicated IP can make sense, but only if you manage it well.
Sender Reputation Tips Across Popular ESPs
Different ESPs handle reputation in different ways, but their advice is similar. They reward clean lists, strong authentication, honest sending practices, and real engagement.
- Mailchimp looks at bounces, complaints, unsubscribes, and engagement.
- Beehiiv stresses verified domains, clean acquisition, and campaign monitoring.
- Substack depends on authentication, content review, and engagement signals.
- Campaign Monitor recommends segmentation, personalization, and steady performance tracking.
- SendGrid gives senders access to account reputation signals and deliverability guidance.
- Sailthru emphasizes opt-in quality, list hygiene, and anti-spam compliance.
- Salesforce points teams toward better list quality, message relevance, and consistent sending.
The common thread is simple. Send to people who asked for your emails. Make the content worth opening. Keep your technical setup clean.
Case Study: Cleaning The Hustle’s List After Bot Attacks
One of our clients, The Hustle, ran into a serious list-quality problem. Subscriber bots were signing up in large numbers. At first, the growth looked positive. In reality, it was hurting the health of the list.
The Problem
The subscriber count rose fast, but engagement did not. Many of the new addresses were fake or low quality. That put pressure on sender reputation and increased the risk of spam-folder placement.
The Diagnosis
Refact audited the list and found suspicious patterns, including zero-engagement users, generic address structures, and behavior that looked automated. Some bots were advanced enough to mimic human activity, which made them harder to spot through standard rules.
The Solution
- We reviewed engagement data and signup patterns in detail.
- We built custom filtering methods to separate likely bots from real subscribers.
- We cleaned the damaged segments and tightened protections around list growth sources.
- We helped protect future operations with better process checks and system logic.
This kind of work often sits between deliverability strategy and backend operations. Stronger automation and integration can help stop bad data from reaching your ESP in the first place.
The Outcome
After cleanup, The Hustle had a stronger list, more reliable data, and a healthier base for future sends. Just as important, the team had better defenses against repeat attacks.
A bigger email list is not always a better email list. If the wrong subscribers get in, deliverability suffers first.
When to Get Help With Email Deliverability
Some problems are easy to spot. Others hide in your setup for months. If open rates are dropping, spam complaints are rising, or your list growth looks strange, it may be time for a deeper review.
Deliverability issues often overlap with site forms, tracking, automations, migrations, and reporting. In some cases, they even point to broader technical problems that deserve an SEO audit and optimization process, especially when email and website performance are tied together.
At Refact, we help newsletter operators and publishing teams solve the system behind the problem. That can include list cleanup, form hardening, platform migration planning, audience workflows, and long-term technical support.
If your emails are missing the inbox or your list quality is slipping, talk to Refact. We help teams find the cause, fix the setup, and protect deliverability before the problem gets worse.