You won’t be rewarded for bad hygiene—in life or in email marketing. Practicing good email list hygiene ensures your content reaches your customers’ inboxes, improving your chances of driving clicks, sales, and better results from your content marketing efforts.
The average email list depreciates in size by about 22% a year, due to people changing email addresses or abandoning accounts. A neglected email list full of inactive subscribers or invalid email addresses can cut into the returns on your email marketing program. That’s why good email list hygiene is a smart investment. Ecommerce open rates average about 31%, so if yours are lower, it may be time to Marie Kondo your email program. Here’s how to get it done.
What is email list hygiene?
Email list hygiene is the practice of decluttering your subscriber list by removing invalid addresses, inactive subscribers, or unengaged recipients. Email providers calculate a sender’s reputation based on bounce rates, spam complaints, and engagement metrics. By regularly organizing and purging contacts that are inactive or invalid, you create an email list of valid email addresses and engaged subscribers who genuinely want your content. Experts recommend using an email validation service and cleaning your list at least twice a year to maintain email health, but larger programs may require more frequent cleaning of harmful addresses. Email list cleaning services are automated and can be an easier way of staying on top of list hygiene.
Not only does a clean email list yield more accurate click-through rates for future marketing efforts, it also reduces your risk of landing in the spam folder by lowering your weighted complaints (WC) rate. WC is the percentage of subscribers marking your emails as spam relative to total sends—one of the key signals inbox providers use to decide whether your messages will reach the inbox or the junk folder.
Risks of poor email list hygiene
Spam complaints are serious business. They damage your email deliverability rate and can even trigger spam traps, where mailbox providers test the legitimacy of your email list. Even a few too many spam complaints can be costly because mailbox providers consider 0.1% the maximum threshold. That’s just one complaint for every thousand emails.
Worse, violations of the CAN-SPAM Act can result in penalties upward of $53,000. Because of laws like this, inbox providers have become more attentive to what users want in their inboxes, vigilant about filtering out invalid email addresses, and determined to catch spammers.
If your email list contains fake email addresses or people regularly marking your content as spam, you risk being blocklisted, which will stall your email program until you take the steps to get delisted.
Cleaning vs. scrubbing an email list: What’s the difference?
Cleaning keeps your email list healthy, while scrubbing keeps your email list active. When you do both, you send emails that are likely to land in an inbox and get traction, engagement, and revenue. Here’s more about how they differ:
- Email list cleaning is about accuracy. This is the technical process of removing invalid email addresses. By cutting bounced contacts, you protect your sender reputation and make sure every email lands in a real inbox.
- Email list scrubbing is about engagement. Scrubbing is the strategic step of analyzing subscriber behavior and engagement rates to segment and to re-engage inactive subscribers.
How email scrubbing works
Here’s a brief breakdown of how email scrubbing works:
1. Remove those who haven’t engaged with your content for three to six months.
2. Create a separate list for them.
3. Create a re-engagement campaign focused on boosting subscriber engagement. Re-engagement campaigns, also known as win-back campaigns, ask targeted list segments who haven’t opened an email in 60, 90, or 120 days if they still want to be contacted.
4. Create a sunset policy to remove them after a certain amount of effort to win them back.
Instead of deleting everyone at once, targeted campaigns give subscribers a chance to raise their hand and let you know they are still interested. As hard as it is to say goodbye to subscribers who remain inactive, those who do not open or interact with your emails only dilute your KPI measurements. By removing inactive addresses, email marketers are able to get accurate data for future engagement strategies.
Example of email hygiene in practice
Regular list cleaning and scrubbing, including email verification, aren’t just smart strategies—they’re also part of widely recommended email marketing best practices. They’re a pre-requisite for email segmentation, which can help increase ROI on email campaigns.
304 Clothing, a Shopify brand, used dynamic segmentation to reduce its email list by 50%, then broke the remaining 50% into 15 segments to send tailored messages. That move helped them double open rates and triple click-throughs in a single quarter, contributing to a 17.5% increase in revenue growth.
How to measure the impact of a clean list
To measure how a clean email list impacts your KPI metrics, you must first get a baseline picture, then measure the difference between the two email lists (the messy one and the clean one). This basically acts as a before and after. Here’s how:
1. Start with a snapshot of your click-through rate, bounce rate, and inbox placement before cleaning.
2. Next, remove invalid, inactive, or risky addresses (spam traps, bounce-heavy, unengaged for more than three months).
3. Track how CTR, CTOR, bounce, and delivery rates change post-clean.
4. Segment-level A/B test. Compare the performance between half the cleaned list and half the messy list.
When you compare, the difference becomes clear: engagement climbs, complaint rates fall, and your messages find their way into a higher percentage of inboxes with a cleaner list. Over time, these improvements compound, showing how list hygiene doesn’t just protect your sender reputation—it amplifies the reach and resonance of every campaign.
How to practice good email list hygiene
- Use double opt-in and email verification
- Review your email list after every major campaign
- Avoid purchasing lists
- Address spam complaints quickly
- Monitor bounce rates
- Watch engagement rates closely
- Manage frequency and recency
- Refresh consent and preferences
Use these steps as guidelines for building your own email list hygiene practice:
1. Use double opt-in and email verification
Implementing email validation through double opt-in can greatly enhance your email health. Double opt-in ensures subscribers confirm their interest via a link in their inbox as well as on your web page. This step weeds out bot sign-ups, typos, and fake addresses before they ever hit your email list.
2. Review your email list after every major campaign
Regularly reviewing your email list is an important step after big marketing efforts like events and promotions, where you gain an influx of new email addresses. If you have an automated welcome series in place, make sure verification happens in real time—using double opt-in or validation tools—so you’re not sending a multi-email series to invalid or risky addresses.
Be sure to verify the accuracy of these contacts prior to sending new campaigns. As part of verification, remove role accounts like hr@company.com from your email list, as they typically are managed by multiple people and can flag your messages as spam. Also, remove obviously fake addresses like those that end with @asdf, @support, or @info.
3. Avoid purchasing lists
It may seem like a shortcut, but these purchased lists are usually outdated, unverified, or just plain uninterested. Because these are not actual subscribers to your content, recipients who do receive these emails are more likely to report them as spam, which will hurt your sender reputation and deliverability rate overall. Not to mention, it also damages customer trust. Growing your email list organically may take a bit longer, but it ensures genuine interest and long-term marketing results.
4. Address spam complaints quickly
One of the most important things to include in every email is a clear way for people to unsubscribe. Due to the CAN-SPAM Act, this is also a legal requirement. At the bottom of every email, brands like Allbirds make it easy for their email list to unsubscribe with a simple click. Failing to include an easy-to-find opt-out link can increase the likelihood that your content will be marked as spam.
Be sure to honor every opt-out request as soon as possible, to include your location in your emails, as it is also legally required, to not use misleading subject lines or heading information, and clearly identify your offer if you are selling something.
5. Monitor bounce rates
If your bounce rates start to climb, it’s a warning sign for email deliverability. Industry experts generally recommend keeping bounce rates under 0.5% to maintain a strong sender reputation. While this number varies slightly by provider, the consensus is clear that even minor increases in bounces can risk email deliverability. HubSpot notes that the average email acceptance rate sits around 99.5%, highlighting how little room there is for error.
Soft bounces—caused by temporary issues on the subscriber’s end, such as a full mailbox—can be monitored and temporarily suppressed. After several weeks of the same addresses bouncing, it’s usually a sign that it’s no longer an active email address, and it’s best to remove them.
Hard bounces, on the other hand, are permanent failures from invalid or non-existent email addresses and should be removed right away. Keeping bounce rates low protects your sender reputation, keeps you in good standing with inbox providers, and saves money by avoiding costs tied to inflated email volumes. Most email service providers (Klaviyo, Mailchimp, Salesforce, etc.) charge based on list size or emails sent. If 10% to 20% of your list is dead weight, you’re paying to send emails to addresses that will never engage.
6. Watch engagement rates closely
Low engagement is a sign that something needs attention. However, it doesn’t always mean your email list is the problem; sometimes it just means your content isn’t hitting the mark, which is why it’s important to know how to tell the difference. If your open rates are low across the board, take a closer look at your subject lines and send times. If people are opening but not clicking, your content or offers may need a refresh. On the other hand, if both are consistently ignored among the same group of subscribers, it’s likely a list-quality issue.
Scrubbing your email list prior to major marketing campaigns helps you pinpoint where to focus your efforts for re-engagement and ensures the performance data is accurate. Creating segments and offering brief opt-out options can help keep your email list healthy so your engagement reflects genuine customer interest, not inflated numbers.
7. Manage frequency and recency
Frequency is how often you send emails, while recency is how recently a subscriber engaged with your email list. Email list hygiene isn’t just about who you send your emails to, but also how often you reach out and how recently they’ve shown interest in you.
- Check send frequency often. Track how often you’re emailing subscribers and see how more or less impacts opens, clicks, and unsubscribes.
- Watch engagement and inbox placement. If engagement dips or more messages land in spam, your email cadence may be too aggressive.
- Optimize your sign-up forms. Let subscribers set their preferences (daily, weekly, monthly) so they stay in control of how often they hear from you.
- Prioritize retention over volume. A smaller list of engaged subscribers is more valuable than a big list of people who ignore your emails.
- Factor in recency. If a segment hasn’t engaged in a while, reduce their email frequency instead of cutting them outright. This lowers the risk of unsubscribes or spam complaints. Some brands even offer an “opt-down” option (fewer emails, not none) to stay connected without overwhelming subscribers.
8. Refresh consent and preferences
A healthy email list strategy acknowledges that preferences don’t stay the same forever. Sending an “update your preferences” email every six months allows people to self-select the cadence and type of content they want in different seasons. Here is an example from Me Undies:
It also shows respect for subscribers’ time, attention, and interests. This small gesture signals that the brand respects what subscribers actually want—putting the customer’s choices at the center of the relationship.
Email list hygiene FAQ
What is email list hygiene?
Email list hygiene is the practice of keeping your email list tidy by actively removing invalid or inactive subscribers, ensuring you are sending emails to real people who actually want to hear from you.
What does a cleaned list mean?
A cleaned list is an email list made of valid, active contacts who are most likely to open, click, and convert.
How often should you clean your email list?
Generally, clean your email list every six months. However, if your list is growing quickly due to high-volume promotions or large batches of new sign-ups, quarterly cleaning can help you stay ahead of bounce rates, spam complaints, and declining engagement.
