How to Improve Email Deliverability in 2025: Avoid Spam and Land in the Inbox

Ever crafted the perfect email, only to see it land in the dreaded spam folder? Frustrating, right? You’re not alone. Email deliverability is a make-or-break factor for eCommerce brands. If your emails don’t reach inboxes, they won’t drive sales.

With mailbox providers fine-tuning their spam filters in 2025, it’s time to step up your game. Let’s break down how to ensure your emails get the visibility they deserve.

1. Email Infrastructure Setup: Build a Strong Foundation

If email marketing were a house, your email infrastructure would be the foundation. A shaky one leads to email deliverability disasters. To stay solid:

• Branded sending domains – Using your own domain (e.g., hello@yourbrand.com) instead of a generic one builds credibility.
• Dedicated IPs – Sending large volumes? A dedicated IP ensures mailbox providers trust you.
• Click tracking domains with SSL – Secure tracking links prevent spam filters from flagging your emails.
• Email authentication – SPF, DKIM, and DMARC are essential for strong email authentication and protecting email reputation.

How to Implement:

• Work with your Email service providers (like Klaviyo, MailChimp, ActiveCampaign, Omnisend, Brevo) to set up authentication records correctly.
• Check your DNS settings using tools like MXToolbox to confirm everything is configured properly.
• Hire a professional email specialist or even an email marketing team to get a proper email infrastructure setup.

2. List Acquisition: Quality Over Quantity

Imagine hosting a party and inviting a bunch of people who don’t care about you. That’s what happens when you send emails to a poorly built list. Instead:

• Never buy email lists – These often contain outdated or spam trap addresses, leading to poor email deliverability.
• Use sign-up forms and lead magnets – Offer valuable incentives to attract engaged subscribers and enhance customer engagement.
• Secure your forms – Avoid bot sign-ups by adding reCAPTCHA or email verification.
• Welcome new subscribers properly – Guide them with an engaging welcome sequence to set the right expectations and improve email campaign optimization.

How to Implement:

• Use double opt-in as a standard practice, but if it’s not for you, here’s how to keep your list clean:

– Real-time email validation via API (e.g., ZeroBounce, NeverBounce, BriteVerify)

– Progressive engagement (ask for preferences, past purchases to verify their activity and interest.)

– Spam protection ( implement Google reCAPTCHA, honeypots)

– Strong welcome email (encourage clicks, preferences, or product exploration)

• Automate a welcome series to educate and engage new sign-ups.

3. List Hygiene: Keep It Clean and Healthy

A messy email list is like a cluttered closet—you need to clean it out regularly. Why? Because sending emails to uninterested recipients tanks your sender reputation.

• Remove unengaged subscribers – If someone hasn’t opened an email in 90 days, it’s time to rethink their place on your list.
• Monitor bounce rates – High bounce rates scream, “bad sender practices!”
• Run re-engagement campaigns – Try to win back inactive subscribers before removing them and keep email engagement high.

How to Implement:

• Use email list segmentation tools like NeverBounce or ZeroBounce to remove invalid addresses.
• Automate a sunset flow to re-engage inactive subscribers before saying goodbye.

4. Email Content: Make Every Email Count

If your emails don’t offer value, your audience will tune out—or worse, mark you as spam. Keep them engaged with:

• Killer subject lines – Skip the generic “Big Sale Today” and spark curiosity instead to improve open rates.
• Personalized content – Show people what actually interests them using behavioral data and email list segmentation.
• Smart recommendations – AI-powered suggestions boost relevance and conversions, improving overall email performance.

For more Best Practices to Boost Sales in 2025 check out our latest article.

How to Implement:

• A/B test different subject lines to see what resonates.
• Use segmentation and dynamic content to personalize every email.

5. Sending Practices: Consistency is Key

Think of email marketing like fitness—you need consistency to see results. Sending in sporadic bursts signals spammy behavior.

• Stick to a regular schedule – Whether it’s weekly or bi-weekly, just be predictable.
• Warm up new domains and IPs – Sudden large sends make you look suspicious and hurt inbox placement.
• Segment wisely – Not every email needs to go to your full list. Targeting improves email engagement.

How to Implement:

• Create a content calendar to maintain a steady sending rhythm.
• Gradually increase email volume when using a new domain.

Real Story: Winning Back an Old Audience (High-Quality Apparel & Tools for Work and Adventure Enthusiasts)

One of our clients, an eCommerce brand founded in 2009, faced a massive email deliverability challenge. After selling the company in 2017, the brand owner returned in late 2024 and wanted to re-engage nearly 200,000 email addresses for a Black Friday campaign. The catch? There had been zero communication for over five years.

This was a high-risk move, but with a strong strategy in place, we made it work. By segmenting the audience based on available data, warming up the list, and carefully crafting content that resonated with past customers, we not only re-engaged the list but also drove a 350% profit increase from the campaign.

The lesson? Even a dormant email list can be revived if you understand your audience, have strong email campaign optimization, and build the right engagement strategy. Find out more Strategy Tips here.

6. Performance Monitoring: Keep an Eye on the Numbers

Numbers don’t lie. Monitoring performance helps you catch problems before they wreck your email deliverability.

• Open and click rates – A drop might mean you’re landing in spam.
• Spam complaints – Keep these under 0.1% or risk getting flagged.
• Bounce rates – More than 2%? Your list needs a cleanup.
• Blacklist checks – Being on a blacklist can devastate your campaigns.

How to Implement:

• Use Klaviyo’s email performance reports to track trends.
• Adjust content, sending frequency, and targeting based on performance.

Real Story: Fixing a Deliverability Crisis

In 2024, we started working with a US-based skincare brand (NDA protected) facing massive Klaviyo deliverability issues with Comcast, Apple, and Microsoft. Blocked IPs meant that 15-20% of their emails weren’t even reaching customers.

Our solution? A deep dive into segmentation and reworking their automation logic. We identified the problem, restructured their sending practices, and optimized their domain reputation. Two months later, their open rates and engagement skyrocketed.

Moreover, the team set up a dedicated IP before the peak Q4 season without turning off any email flows! This kept revenue steady while ensuring the business was ready for the busy season with no impact on deliverability.

Btw, we’re still working with them! This collaboration expanded from fixing deliverability to full technical and strategic support for both Email and SMS Marketing in Klaviyo.

How to Implement:

• Use Klaviyo’s email performance reports to track trends.
• Adjust content, sending frequency, and targeting based on performance.
• Use Klaviyo’s email performance reports to track trends.
• Adjust content, sending frequency, and targeting based on performance.

Final Thoughts

Mastering email deliverability isn’t about tricks—it’s about building trust, maintaining a clean and engaged list, and continuously optimizing your email marketing strategy. Staying proactive in your monitoring, segmentation, and email campaign optimization will set you apart from competitors stuck in the spam folder.

Consistency is key—keep refining your email list segmentation, stay compliant, and always put your audience’s needs first. Email deliverability is not just a technical issue; it’s an ongoing strategy that keeps your brand relevant and profitable.

If you want to elevate your email marketing and ensure your messages consistently reach the inbox, our team at IMPRO is here to help. Let’s chat!