Every day, 347 billion emails are sent worldwide. Of those, 160 billion are spam.
That’s a huge challenge for inbox providers like Google and Yahoo, who are tightening their filters to protect end users. In 2024, they set a strict spam complaint threshold of just 0.3%. Cross that line, and you risk being blocklisted.
When that happens, your emails stop reaching your audience. Your sender reputation drops. Even if some emails slip through, they’re often buried deep in the spam folder. Or worse, providers might even block your domain altogether. That’s the harshest blow to your deliverability and reputation.
Deliverability depends on many things, and your email list is one of the most important.
An email list brimming with disengaged or invalid addresses is a loud signal to mailbox providers that you’re not focusing on list hygiene. And that’s an easy way to smear your sender reputation. On the contrary, nearly half of marketers who focus on list hygiene report that maintaining a strong sender reputation is their biggest win.
Said another way: if your email list isn’t healthy, your deliverability—and the return on your marketing efforts—could suffer.
Let’s understand how to keep your list clean, compliant, and full of engaged subscribers.
What Is Email List Hygiene?
Experts in the Email Marketing Trends 2025 infographic by Email Mavlers are calling deliverability the biggest email trend this year. With the focus shifting toward smarter list management, brands will have to build more targeted, high-quality lists to avoid deliverability issues. That brings a renewed awareness to email list hygiene.
Email list hygiene is the process that keeps your email contact list viable to send campaigns. Good list hygiene is important because it maintains valid and engaged subscribers on the list and removes problematic contacts off your database.
It’s like brushing your teeth, but for your email marketing, that keeps your contact list fresh, functional, and free of junk.
Good list hygiene means you send your emails to contacts who want to receive them. They are valid, engaged subscribers who open, click, and engage.
However, to keep your email list healthy, you also need to remove the email addresses that weigh you down. From outdated addresses, fake signups, and unengaged subscribers to duplicate contacts. Email list hygiene removes all of those who are just taking up space and damaging your sender reputation.
Unsurprisingly, email list hygiene is one of the best measures to improve the deliverability of your emails. Do it regularly, and you only reach valid contacts. This reduces your chances of hitting spam traps.
However, if you skip this step, things start to go awry. Nearly 40% of marketers rarely or never clean their lists. That neglect manifests as poor open rates, higher bounce rates, and more emails landing in the spam folder (or not landing at all).
If you belong to that 40%, know that you’re self-sabotaging your email marketing efforts, and deliverability issues are inevitable.
For a deep dive into improving email deliverability, catch the conversation between Mavlers and Andrew King, Email Love here.
Common Email List Hygiene Mistakes That Hurt Your Deliverability
- You’re not verifying your list regularly
Email lists decay each year as people change jobs, abandon old inboxes or unsubscribe. Outdated or inaccurate data like this hurts personalization and lowers engagement. Regular verification keeps your data clean and campaigns effective.
- You do not segment your email listÂ
Sending the same email to your entire list is a fail-safe way to disengagement. Without segmentation based on interests, behaviors, or demographics, your emails feel irrelevant. This leads to lower open rates and higher unsubscribe rates.
- You’re sending emails without permission
You’re not wrong to get tempted to buy email lists, but it hurts your sender reputation. These recipients haven’t opted in, which means they’re more likely to flag you as spam. Plus, it can also violate laws like the CAN-SPAM Act.
- You ignore spam complaintsÂ
Spam complaints and unsubscribe rates are warning signs, not just numbers. High complaint rates tank your sender reputation and deliverability. Always monitor feedback loops, make unsubscribing easy, and adjust your content or frequency based on what your audience tells you.
6 Best Ways to Build and Maintain a Healthy Email List
An email list is your most valuable asset till it’s filled with valid email addresses. How your email list is built has a lot to do with the quality of engagement it sparks and, hence, your sender reputation.
To build a healthy email list:Â
- Be Transparent and Compliant While Collecting EmailsÂ
No funny business here. Be as clear as day in letting subscribers know what it is that they are signing up for. A newsletter, product updates, or promotional offers. And always, always let them explicitly opt in to receiving marketing messages by avoiding vague language and pre-checked boxes.
Be aware of GDPR, CAN-SPAM, and other data privacy regulations. Clearly display your privacy policy and be upfront about how subscriber data will be used. And make unsubscribing easy.
- Use Double Opt-In to Ensure List Quality
Building a deliverability-friendly email list starts with one core principle: only target active and engaged users. Double opt-in is the most effective way to identify such users.
Single opt-in adds users to your email list after just one form submission. In comparison, double opt-in has an extra verification step.
After someone enters their email address in a signup form, you send them a confirmation email. It asks them to click a link to confirm their subscription to receive your emails in the future.
Sure, it’s an extra step. But think about what this simple process weeds out: fake email addresses, bots trying to mess with your list, typos (you know, like “gmial.com”), and people who weren’t paying attention when they signed up.
It’s also your best defense against spam traps—those sneaky fake addresses designed to catch senders who aren’t careful about list quality. Hit one of those, and your sender reputation takes a serious hit.
From a compliance standpoint, it covers GDPR and other data protection regulations by capturing clear, trackable consent.
Most importantly, you have people who take the time to confirm their subscriptions and are genuinely interested in your emails. They open emails more often, click more links, and are more likely to buy from you. That’s because they made a deliberate choice to be there.
- Launch an Industry Newsletter
A well-crafted industry newsletter is a magnet for the right subscribers. Share insights, trends, and tips that position your brand as a go-to resource. When your newsletter delivers real value, word spreads—and your list grows with engaged, relevant contacts who look forward to your updates.
Launch an industry newsletter that delivers real value. Share insights, trends, and tips that position you as a trusted resource. When your content is genuinely helpful, it’s easier for you to grow a list of engaged contacts.
The best part is that consistently high-quality content helps Email Service Providers (ESPs) determine your inbox placement and that your emails deserve to reach the intended inboxes.
- Give People the Choice to Subscribe to Deals or Product Updates
Some subscribers don’t want a full newsletter. They just want to know when something’s on sale or a new product drops. That’s okay. Give them the option to choose what they sign up for. This will only improve sign-ups and reduce unsubscribes later.
- Offer Valuable Content in Exchange for Contact Info
Want someone’s email address? Give them a reason to hand it over. Ebooks, templates, exclusive discounts, or free tools work because they provide immediate value.
Just make sure your lead magnet attracts the right people.
- Use Signup Forms WiselyÂ
Place signup forms where your audience is most engaged—on your website, blog, social media, and at events. Use clear calls to action and incentives that attract the right people, not just anyone. Protect your forms with CAPTCHA or real-time validation to keep bots and fake signups off your list.
Wrapping Up
The more your subscribers open, click, reply to, or even forward your emails, the stronger the signal you send to mailbox providers that your emails are valuable and worthy of the inbox, not the spam folder.
But this level of engagement doesn’t happen by accident. It starts with a clean, well-maintained email list full of engaged subscribers. Only then will your deliverability improve.
If managing all this feels like a full-time job (because it is), working with email experts like those at Email Mavlers can make a world of difference. From list hygiene to smart segmentation and design, teams that live and breathe email know how to help your campaigns stay out of trouble.
