How to Improve Email Deliverability

Do you need to improve email deliverability? Imagine this scenario: You spent an hour writing that campaign email. You crafted a subject line, checked it twice, and hit send to your list. Then: nothing. Low opens. No clicks. No replies.

Before you rewrite the message, consider this: the problem might not be what you wrote. It might be that no one saw it at all.

Email deliverability is the invisible factor behind every campaign you send. When it breaks down, your emails end up in spam folders, are quietly filtered out, or never make it past the first checkpoint. When you improve email deliverability, your messages land in the inbox where people can actually read them.

The good news is that email deliverability is not a technical mystery reserved for IT departments. It is a set of practices any small business owner can learn, apply, and maintain. This guide walks you through the essentials. What it means to improve email deliverability, why it fails, and the practical steps you can take today to fix it.

What It Actually Means to Improve Email Deliverability 

Most people assume that if an email is sent, it is delivered. That assumption is costing them.

Email deliverability is the likelihood that the email you send will reach your contact’s primary inbox, where it can be seen and acted on. It is different from the two metrics that often get confused with it.

Delivery rate measures whether the recipient’s server accepted your email without bouncing it. An email can have a 100% delivery rate and still land in the spam folder. Delivery is a pass/fail checkpoint at the door. Deliverability is whether you made it to the table.

Open rate measures how many people opened an email that was already in their inbox. Open rate is downstream of deliverability. If your emails are being routed to spam, your open rate will look low, but the real problem happened before the email was ever seen. It is worth noting that since Apple introduced Mail Privacy Protection, up to 52% of reported email opens may be unreliable. For small business owners who want an honest read on engagement, click-through rate is now the more accurate metric to watch.

Understanding this distinction matters because it changes where you look when something is wrong. Low opens do not always mean weak subject lines. Sometimes they mean your emails are not reaching the inbox in the first place.

Why Your Emails Are Getting Blocked

Inbox providers like Gmail, Outlook, and Apple Mail use sophisticated filters to decide what reaches your contacts and what gets routed away. They are protecting their users, which means they are constantly evaluating you as a sender. Here are the most common reasons small business emails fail those evaluations.

Purchased or unverified lists. If you bought a list or added contacts without their explicit consent, those recipients never asked to hear from you. Inbox providers quickly recognize the pattern, and your mail gets flagged as unsolicited. This is the fastest way to damage a sending reputation that took months to build.

High bounce rates. Bounce rate in email marketing is one of the most pernicious blockers. Sending to a stale list of outdated or invalid email addresses signals to providers that you are not maintaining your data. HubSpot, along with most major email platforms, will suspend your sending privileges if your hard bounce rate exceeds 5%. A clean list is not optional — it is a baseline requirement.

Low engagement history. When recipients consistently ignore your emails — no opens, no clicks, no replies — or worse, mark them as spam, your sender reputation drops. Providers use that signal to decide how much trust to extend to future messages from your domain.

Spammy content signals. Certain words and patterns in your subject line and body copy trigger spam filters. Subject lines loaded with urgency phrases, excessive punctuation, or all-caps formatting raise immediate red flags. A balanced, straightforward subject line will almost always outperform a pushy one.

Design imbalances. Emails built primarily from images with very little readable text are a common deliverability problem. Large image files that load slowly also create friction. A healthy text-to-image ratio, web-optimized images under 200KB, and alt text for every image will serve both your deliverability and your accessibility.

The Foundation: Email Authentication

Before you address list quality or content, your domain needs to be authenticated. Authentication is how you prove to the internet that the emails coming from your domain are legitimate. Think of it as a driver’s license for your brand.

There are three records that work together to establish that proof.

SPF (Sender Policy Framework) is a record that lists the IP addresses authorized to send email on behalf of your domain. When a receiving server gets your email, it checks this list. If your sending IP is on it, the email passes the first test.

DKIM (DomainKeys Identified Mail) adds a digital signature to your outgoing emails. That signature travels with the message and allows the receiving server to verify that the content was not altered in transit. It is an integrity check that protects both you and your recipients.

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is the policy layer that ties SPF and DKIM together. It tells receiving servers what to do if an email fails either of those checks — quarantine it, reject it, or let it through and report back to you. A properly configured DMARC record also prevents bad actors from sending fraudulent emails that appear to come from your domain.

If these three records are not set up, you are operating without credentials. Most small business email platforms — including HubSpot — provide guidance on setting them up, and tools like MXToolbox allow you to check the status of your records for free.

How to Improve Email Deliverability: A Step-by-Step Approach

With the foundation in place, here is how to build and maintain strong deliverability over time.

Step 1: Audit Your Sender Reputation

Your sender reputation is the score inbox providers have already assigned to your domain based on your sending history. Before you change anything else, you need to know where you stand.

Google Postmaster Tools provides a free dashboard that shows your domain reputation, spam rate, and authentication status specifically for Gmail, which handles a significant portion of email traffic. MXToolbox offers a broader look at your domain’s DNS records, blacklist status, and authentication configuration. Check both before you proceed.

If you discover that your domain is on a blacklist, do not panic. Most blacklists provide a removal request process. Cleaning up the practices that led to the listing is more important than the removal itself — if you do not fix the source, the problem will return.

Step 2: Set Up and Verify Your Authentication Records

Use MXToolbox or your email platform’s built-in tools to confirm that your SPF, DKIM, and DMARC records are live and configured correctly. If any are missing or misconfigured, work with your domain registrar or hosting provider to set them up. This is a one-time technical step with long-term benefits.

Step 3: Clean Your List

A smaller, engaged list will always outperform a large, disengaged one. Be vigilant of your bounce rate in email marketing. Go through your contacts and remove hard bounces immediately. Additionally, unengaged or disengaged contacts should never receive any more emails. For contacts who have not opened or clicked anything in the last six months, consider a re-engagement campaign before sending your next regular email.

That re-engagement campaign does not need to be complicated. A single email with a subject line like “Still want to hear from us?” and a clear yes/no option is enough. Contacts who do not respond to re-engagement should be suppressed from future sends. This practice is sometimes called a sunset policy, and it is one of the highest-impact list maintenance habits you can build.

A related concept worth knowing is graymail: emails sent to people who gave consent but have since stopped engaging. Continuing to send to graymail contacts erodes your reputation gradually. A re-engagement campaign addresses both problems at once.

Step 4: Build Better Sending Habits

Deliverability is not just about setup — it is about consistency. Here are the habits that protect your reputation over time.

Send on a regular schedule. Sudden spikes in send volume look suspicious to inbox providers. If you typically send 200 emails a week and suddenly send 2,000, expect increased scrutiny.

Use a verified sending domain, not a free webmail address. Emails sent from @gmail.com or @yahoo.com on behalf of a business are immediately flagged by filters.

Always include a valid physical mailing address and a clear unsubscribe link. This is not just best practice — it is a legal requirement under the CAN-SPAM Act. Violations can result in fines of up to $46,517 per email, which is a consequence no small business needs.

Get explicit consent before adding anyone to your list. Contacts who asked to hear from you are more likely to engage and far less likely to report your emails as spam.

Step 5: Warm Up a New Domain

If you are starting fresh with a new sending domain, do not blast your full list on day one. New domains have no reputation history, and inbox providers treat them with the same skepticism they would apply to anyone without a track record.

Start by sending small volumes to your most engaged contacts — the people most likely to open, click, and reply. Gradually increase your send volume over several weeks as you build a positive engagement history. This process is called domain warm-up, and skipping it is one of the most common reasons new email programs fail out of the gate.

What Good Looks Like: Benchmarks to Aim For

Knowing your numbers gives you something concrete to work toward. Here are the key metrics and thresholds that indicate a healthy sending program.

Hard bounce rate: Keep this below 2% as a general target. At 5%, most email platforms will intervene.

Spam complaint rate: Google recommends keeping this below 0.10%. Above 0.30% triggers serious deliverability consequences.

Click-through rate: Given the unreliability of open rate data under Apple’s Mail Privacy Protection, CTR is your most honest measure of engagement. Industry averages for B2B email hover around 2-5%, with well-segmented lists consistently performing above that range.

Unsubscribe rate: A rate below 0.5% per send is generally considered healthy. A spike in unsubscribes is a signal worth paying attention to — it usually points to a relevance or frequency issue.

These numbers are not ceilings. They are floors. A well-maintained list with genuinely useful content will consistently outperform them.

The Tools That Help

You do not need a large technology budget to monitor and improve email deliverability. A few well-chosen tools will give you most of what you need.

Google Postmaster Tools (free) tracks your domain reputation and spam rate specifically for Gmail recipients. If a significant portion of your list uses Gmail, this dashboard is essential.

MXToolbox (free tier available) checks your DNS records, authentication setup, and blacklist status. It is the fastest way to identify configuration problems.

HubSpot Email Health Tool (included in HubSpot Starter) provides a 30-day view of your reputation and compares your performance against industry benchmarks. If you are already using HubSpot for email, this is the first place to look.

HubSpot Email Analyze Page allows you to visualize your metrics over specific timeframes, making it easier to spot spikes in bounces or unsubscribes before they become serious problems.

WebAIM Color Contrast Checker (free) is worth mentioning here because accessibility and deliverability overlap more than most people realize. An email that is hard to read for users with visual impairments is also more likely to generate negative engagement signals.

You Do Not Need to Become a Tech Expert

Improving email deliverability can feel like a technical mountain when you first look at it. DNS records, authentication protocols, sender reputation scores — the vocabulary alone is enough to make most small business owners step back.

But here is what matters in your efforts to improve your email deliverability: you do not need to master every technical detail. You need a process. Set up your authentication once and leave it. Clean your list on a regular schedule. Send consistently, get consent, and pay attention to your engagement metrics. That combination covers the vast majority of deliverability problems before they start.

The business owners who get this right are not the ones who became email experts overnight. They are the ones who took a few focused steps, built the right habits, and stayed consistent.

Start with your sender reputation audit. Check your authentication records. Then take one list-hygiene step this week. That is enough to move the needle and improve your email deliverability. Purposeful Media Promotions specializes in B2B email marketing management and remediation. Reach out to us if you want to start a conversation, analyze your resources, and improve email marketing outcomes for your organization.