How to Improve Email Deliverability: 6 Techniques and Tips That Work

Just before you get yourself worried about low conversions in your email marketing strategy, why not find out if your emails actually got to your recipients' inboxes?

Email remains a critical form of communication for businesses in this digital age, but ensuring that your emails reach the intended recipients can be a challenge. It's a futile effort to spend time crafting an engaging newsletter only for it to land in the spam folder. In 2022, the average inbox placement rate (IPR) globally was just below 85%, meaning that roughly 1 in 6 messages never made it to the inbox at all.

Poor email deliverability leads to lost sales opportunities, damaged brand reputation, diminished customer trust, and wasted marketing spend. Deliverability is the metric every other metric depends on: open rate, click rate, and conversion only matter once the message lands in the inbox. This guide walks through what affects deliverability, six techniques to improve it, and how to adapt your approach depending on whether you're sending sales outreach, transactional emails, or high-volume programmatic campaigns.

Factors that influence email deliverability

• Sender's reputation
• Email content
• IP address
• Spam complaints from recipients
• Quality of your email list
• Email volume
• Sending frequency

The 6 techniques that improve email deliverability

Now that you know what affects deliverability, here are the six strategies that will get your email directly into your recipient's inbox instead of their spam folder.

• Building and Maintaining a Quality Email List

The foundation of good email deliverability is a high-quality email list. Here's how to build and maintain one:

• Use Double Opt-In

Double opt-in requires users to confirm their subscription by clicking a link in a confirmation email. This method ensures that the email addresses on your list are valid and that subscribers genuinely want to receive your emails.

• Regularly Clean Your List

Remove inactive subscribers and invalid email addresses from your list periodically. This helps maintain high engagement rates and reduces the chances of being flagged as spam.

• Avoid buying ready-made lists

Purchased lists often contain outdated or invalid email addresses, leading to high bounce rates and spam complaints. Build your list organically instead, through lead magnets, social media, and gated content.

2. Authenticating Your Emails

Email authentication verifies the authenticity of the sender and proves that the email is coming from a legitimate source. It's one of the fastest ways to improve email deliverability because it establishes trust with email service providers.

• Implement Sender Policy Framework (SPF)

SPF is an email validation system designed to prevent spammers from sending messages on behalf of your domain. It specifies which mail servers are permitted to send emails on behalf of your domain.

• Use DomainKeys Identified Mail (DKIM)

DKIM adds a digital signature to your emails, allowing the recipient's server to verify that the email was not altered during transit and that it genuinely comes from your domain.

• Enable Domain-based Message Authentication, Reporting & Conformance (DMARC)

DMARC builds on SPF and DKIM, adding an extra layer of security by allowing domain owners to specify how unauthenticated emails should be handled. It also provides reports on email authentication performance.

3. Monitoring Your Sender Reputation

One important factor that impacts your email deliverability is "who" is sending it. ISPs use sender reputation to determine whether your emails should be delivered to the inbox or the spam folder, and they'll block emails from suspicious sources outright.

• Maintain Low Bounce Rates

Monitor your bounce rates. High bounce rates can damage your sender reputation. Keep your email list clean and up to date to avoid sending to invalid addresses.

• Reduce Spam Complaints

Encourage subscribers not to mark your emails as spam, or ISPs will start treating your future sends as suspect. Provide clear unsubscribe options and keep the content relevant.

• Use a Consistent Sending Schedule

Manage your sending frequency to keep readers engaged without overwhelming them. Irregular sending intervals can trigger spam filters, so ramp up your sending schedule gradually and stay consistent to protect a positive sender reputation.

4. Crafting Engaging and Relevant Content

Content quality affects email deliverability more than most people expect. Engaging, relevant content encourages recipient interaction, and that interaction signals to ESPs that your emails are worth delivering.

• Personalize Your Emails

Personalization boosts engagement rates. Use subscriber data to tailor your emails to each recipient's demographics, preferences, and behavior (our guide on the benefits of email personalization covers this in more depth).

• Avoid misleading subject lines

Create subject lines that are catchy but still relevant to the content of your email. Keep it concise, around 30-40 characters, personalize with the recipient's name where possible, and spark curiosity. Our guide on writing subject lines that boost open rate goes deeper into this.

• Avoid Spam Triggers

Certain words and phrases trigger spam filters. Avoid all caps, excessive punctuation, oversized embedded images, and words like "free" or "urgent" in subject lines and body copy. Focus on real value rather than a sales gimmick.

• Include a Clear Call-to-Action

A clear call-to-action (CTA) encourages recipients to interact with your email. Don't assume recipients know what to do next: tell them, whether it's visiting your website, watching a video, or making a purchase. More interaction signals to ESPs that your emails are legitimate and valuable.

5. Optimizing for Mobile Devices

A large share of emails are opened on mobile devices. Make sure yours are mobile-friendly to avoid high bounce rates and low engagement.

• Use Responsive Design

Responsive design ensures your emails look good on any device, whether that's a smartphone, tablet, or desktop.

• Keep Subject Lines Short

Mobile devices display fewer characters in the subject line. Keep yours concise and compelling to capture attention before it gets cut off.

• Optimize Images

Large images slow down load times on mobile devices. Use compressed images for faster loading and a better experience.

6. Testing and Analyzing Your Emails

There's no single fix that guarantees inbox placement, so continuous testing and analysis are what actually move the needle over time.

• A/B Testing

A/B testing involves sending two versions of an email to a small segment of your list to see which performs better. Test different subject lines, content, and CTAs to optimize your emails.

• Monitor Key Metrics

Track open rates, click-through rates, bounce rates, and spam complaints. Use these insights to refine your email strategy.

• Adjust Based on Feedback

Feedback from subscribers can provide valuable insight into what's working and what isn't. Use it to make necessary adjustments to your campaigns.

Sales email deliverability tips

Sales outreach behaves differently from newsletter sends, so it deserves its own set of email deliverability tips. Sales teams typically send lower volume but higher personalization, often from individual mailboxes rather than a bulk sending domain, and that changes what actually moves the needle.

• Warm up new mailboxes gradually. A brand-new sales inbox that sends 200 cold emails on day one will get throttled or flagged almost immediately. Ramp up volume over two to three weeks.
• Keep send volume per mailbox low and steady. Spreading outreach across multiple properly authenticated mailboxes protects deliverability better than pushing everything through one address.
• Watch reply and bounce rates closely. Sales lists change fast. Job changes, invalid addresses, and gatekeeper bounces all erode sender reputation quickly if you don't clean the list often.
• Avoid link-heavy, template-heavy emails. Highly templated sales emails with multiple tracking links are exactly what spam filters are tuned to catch. Keep sales emails closer to how a real one-to-one email reads.

These are the same fundamentals behind improving email deliverability for sales in general: reputation, authentication, and list hygiene, just applied at the mailbox level instead of the domain level.

Deliverability for programmatic and transactional sending

Sending at scale changes the calculus again, whether that's programmatic campaigns, product notifications, or transactional emails like receipts and password resets.

• Separate sending domains or subdomains by email type. Transactional and marketing email have different engagement patterns. Mixing them on the same sending domain means a rough marketing campaign can drag down deliverability for password-reset emails that absolutely need to land.
• Prioritize speed and consistency for transactional sends. Transactional emails are expected to arrive in seconds. Route them through infrastructure that isn't queued behind bulk marketing sends.
• Monitor deliverability per channel, not just in aggregate. If you're improving deliverability across all channels, including email, SMS, and in-app, track each one separately. A problem in one channel can mask a healthy trend in another if you only look at a blended number.
• Watch engagement signals at scale. Programmatic sending can outpace your ability to manually catch a reputation problem. Automated alerts on bounce rate and spam complaint thresholds catch issues before they snowball.

Email marketing tools and software

Email marketing tools and software can also help improve your deliverability rates. A platform like Circle helps increase your email deliverability through personalized email campaigns, whether you're running SaaS email marketing sequences or one-off sales sends. The platform schedules campaigns at optimal times, and you can track and analyze the performance of your emails to see what to improve next, including how your transactional messaging is performing separately from marketing sends.

Conclusion

Mastering email deliverability is an ongoing process, not a one-time fix. Build a quality email list, authenticate your emails, protect your sender reputation, write content people actually want to open, optimize for mobile, and keep testing your campaigns. Do that consistently and deliverability improves, whatever the sending use case.