A Guide To List Hygiene Best Practices
If you’re responsible for email marketing and CRM management, you’ve probably encountered the terms list cleaning or list hygiene. They mean: keeping your list “clean” in order to see high performing results from email marketing. It’s an often overlooked aspect of maintaining high-performance campaigns.
Over time, your email list needs to be culled in order to continue to have high results from email.
Why List Cleaning Is Important
Whether you’re in a B2C business or a B2B business, there are a lot of reasons the email addresses you captured 10 years ago are probably not serving you:
- Email accounts that are no longer active or used
- Business email accounts that change because they changed roles
- Bounces because the inbox is full
- Typos on signups from bots and spam traps
Ensuring that your contact lists are up-to-date and error-free can significantly impact your business outcomes.
Good list hygiene improves email deliverability, allows for better segmentation—leading to more targeted marketing, helps in reducing billing costs for services based on the number of contacts, and makes it much easier to migrate data should you switch platforms in the future.
Basic Approach to List Cleaning
People often get lost in the details, but the basic approach to list cleaning is actually very straightforward.
Step 2: Suppress or delete them in your email marketing provider.
Step 3: Repeat every 6 months (This exercise gets easier and less significant with consistent cleaning).
1. Defining Active Email Addresses
What you define as an “active email address” will depend on your business and what data you have available on them from your email service provider (ESP) and data collection process. While there is no one-size fits all, there are some best practices:
For any business, it’s a good idea to regularly check and remove bounced emails. This may be done automatically by your ESP.
It’s also a good idea to remove people that have not engaged with your last 6-12 months of emails. If you’ve been sending them emails and they’re not biting – meaning opening emails, visiting your website, or showing signs of still being interested in your business and what you have to offer – it’s time to remove them.
In any business, you want to try to define those who are active, so that it will be easier to identify those who are inactive.
If you’re an e-commerce business, you likely have a lot of data about people in your ESP: If they’ve purchased from you, viewed a product page, or started checkout. Keep those that have shown interest.
If you’re a B2B business, you likely have data about how they’ve interacted with your team: If they’ve submitted a contact form, joined a sales call, been a past client or referral partner, or downloaded a guide. Keep those who have engaged.
In our business, we define inactive as someone who:
- Has received 10 emails from us in the last 12 months
- Has not opened emails or clicked emails from us in the last 12 months
- Has not purchased from us in the past
- Has not visited our website, started checkout, booked a sales call
2. Managing Inactive Email Addresses
Congratulations, you’re halfway there. Next, you have to decide what to do with these inactive emails. Each ESP will be slightly different. You’ll want to check the support documentation of your ESP and understand how you are being billed – this is key. The idea is you aren’t going to be emailing inactive profiles, so you don’t want to have to pay for them.
In HubSpot, this could mean you decide to set these contacts as “non-marketing contacts.” In Klaviyo, it could mean you decide to suppress these contacts.
It’s always better to preserve the data of inactive email addresses if it’s possible to do so. If you’re not sure, start a support ticket with your ESP and ask them what the best way is to manage this. If for some reason you do have to delete them from your ESP, take a moment and back up the data for their profiles first.
Managing Inactive Emails By Email Service Provider |
||||
|---|---|---|---|---|
| Mailchimp | Klaviyo | HubSpot | Omnisend | |
| Billing Basis | Billing includes total subscribed, unsubscribed, and non-subscribed contacts. | Billing includes all active email profiles (subscribers + non-subscribed contacts). | Only marketing contacts count toward billing. | Billing includes all active subscribers + non-subscribed contacts receiving automated emails. |
| How to remove a contact from billing | Contacts can be archived to remove from billing. | Suppressed profiles don’t count toward billing. | Non-marketing contacts don’t count toward billing but still exist in CRM. | Suppressed contacts don’t count toward billing. |
| Articles & Links | ||||
If you need more help, consider an email marketing audit and we can guide you through the process, taking into account your unique business and data.
Advanced Cleaning Strategies
Those are the basics, but as an email marketing agency we can get pretty advanced when it comes to list cleaning. We see the benefits, and the direct impact on deliverability, so we’ve developed strategies to “clean along the way.”
Just like a house cleaner will tell you it is always preferable to clean regularly so the “deep cleans” aren’t as intensive, the same concept applies to cleaning your email list.
And the good news is, there are ways to put this cleaning on autopilot so you don’t have a daunting deep clean to do.
Here are a few strategies you might consider exploring if you haven’t already.
Running a re-engagement campaign before removing an email: Re-engagement, or win-back email campaigns invite people to remain engaged with your company before you stop emailing them. You can do this in a variety of ways. Maybe it’s announcing news that might have gotten missed or offering something new to them. Sometimes it’s sending personalized emails stating that you miss them.
Automate marking email lists as inactive: Most tools, like Klaviyo and HubSpot will let you create “inactive profile” segments and they just keep running. Anytime someone meets your defined conditions, they’re entered into the segment. What this means is that your list cleaning gets a lot easier, you don’t have to start from scratch. Go in every 6 months and empty that segment.
Should You Use An External List Cleaning Tool?
We get this question a lot: Are external list cleaning tools necessary? An email validation tool lets you run a list of emails through them for a fee, and return data to you about the addresses’ validity. That can be used as part of list cleaning when you don’t have enough data to identify whether the email address is active.
As an agency, we use them often for this purpose. Conduct a thorough cleaning, then set up a re-engagement campaign, and have minimal ongoing cleaning. This is a very simple and straightforward project for us as CRM experts.
Here’s an overview of a few external tools to give you an idea. There are many on the market, and they do more than just help you clean your list, so choose wisely.
| Tool | Price | Good for | Key Integrations |
|---|---|---|---|
| Dropcontact | $1249 (100k credits) | B2B Email finding | HubSpot, Zoho |
| Zero Bounce | $425 (100k credits) |
Email verification, Email finding, Blacklist monitoring |
ActiveCampaign, MailChimp, Klaviyo, HubSpot |
| Alfred | From $540 (100k credits) |
Free email verification preview, Ready-to-go segments |
Klaviyo, Yotpo, Digioh |
ZeroBounce is perfectly fine if you’re really working with high volumes. But if you do this regularly, we recommend taking a look at Alfred because of its features – easily saves a few hours and makes it worth the added expense in our experience.
However, at the end of the day any reputable list cleaning tool will be a good idea.
The important thing with any of these tools is that to keep your costs down, you really want to run the minimum through it. Meaning, don’t fall into the trap of “running your whole list through an external service.” Use your ESP to create a segment of “likely inactive” addresses first. If someone is active, you don’t need to review their email list.
Maximizing Email ROI
When it comes to email marketing, maintaining a clean list isn’t just about deliverability – it’s about your bottom line. Costs are increasing across the board. Every contact you keep represents a cost, whether in your ESP billing or in potential deliverability issues that could harm your sender reputation and your email marketing ROI.
The most cost-effective approach to list hygiene is prevention. By implementing regular cleaning practices, you’ll spend less time and money on major clean-up projects in the future.
Overwhelmed with your list hygiene project? At Centric Squared, we specialize in email marketing and have deep CRM expertise to make sure your list is always in great shape for maximum results. Ready to improve your email marketing ROI? Book a call with our team today, and let’s see how we can help you.
FAQ: Email List Cleaning
Here are some frequent questions we get about list cleaning.
1. What does list cleaning have to do with deliverability?
An old or unculled email list full of inactive or invalid addresses can hurt your sender reputation and deliverability. When too many emails bounce or go unopened, inbox providers (like Gmail or Outlook) may start flagging your emails as spam, lowering your email deliverability. Keeping your list clean helps ensure your messages are being sent to those who will open them, which creates a positive feedback loop and pulls up your sender reputation and repairs your email deliverability.
2. How often should I clean my list?
We recommend businesses that have been running email for over 2 years without list cleaning to do a deep clean. Then, do a basic check and cull every six months. If your email metrics are dropping and you are noticing deliverability issues, it’s a good idea to spot-clean too. If you suddenly have an influx of emails and high sending period, it’s a good idea to clean your list afterward.
3. My ESP doesn’t make it easy to clean my list—what should I do?
Many Email Service Providers (ESPs) don’t offer built-in list cleaning tools. In that case, you can:
- Export your lists to identify manually (in Excel) any active or inactive subscribers.
- Use a third-party email verification service like ZeroBounce, Dropcontact, or Alfred to identify invalid emails.
- Manually export, clean, and re-import your list with only verified and active addresses.
- Still need help? Our agency can help. Book a call.
4. Should I delete or suppress profiles—what’s the difference?
- Deleting an email removes it from your database completely. You lose all historical data.
- Suppressing an email keeps the profile in your system but prevents future emails from being sent. This is useful if someone unsubscribes or marks you as spam.
Generally, suppressing is better for compliance and future insights. Check with your ESP on how to do this; each one has a different set of terminology and billing practices.
5. Our management team doesn’t want our email list to take a hit—what should I do?
It’s common for leadership to worry about list size vs. list quality. Here’s how to address this:
- Show the data: A clean, engaged list improves open rates, click rates, and conversions. Keeping disengaged contacts only hurts email performance and increases costs.
- Run a re-engagement campaign first: Before removing inactive contacts, give them one last chance to stay in.
- Highlight cost savings: Many ESPs charge based on list size. Removing inactive emails reduces expenses. Explain how this impacts ROI over time and what the cost of this vanity metric really is.
6. Do I need to tell people I’m removing them from our list?
Not necessarily, most take “not engaged over a long period of time” to mean they are not interested any longer. But if you want to give subscribers a final chance, you can send a “Last Chance To Stay Subscribed” email. If they don’t engage, it’s best to remove or suppress them.
7. What happens if I’ve suppressed someone and they come back to our website?
They will have to opt-in again to receive emails from you. This will activate them and move them out of the suppression status. However, if they don’t re-subscribe, they’ll remain suppressed and won’t receive emails. If this is part of your strategy, consider updating your FAQ page with a “Why am I not receiving emails” section and include a link to opt in.
8. Do I need to delete unsubscribed emails?
It depends on your Email Service Provider, but usually there is a way to keep unsubscribed emails without paying for them. It’s nice to keep a history of unsubscribes because quite simply, if someone has said “don’t email me,” you need to respect that.
9. Why do I need to pay for people I’m not emailing? Can’t I just keep them and not send emails?
Email has grown and many ESPs are updating or changing their billing policies to charge for anyone you are able to email. The reason they give is that they are storing data, and that has a cost which they transfer to you. Cleaning your list helps lower costs. It’s always smart to consult with your ESP directly though; these rules and details are changing fast.
10. When do you need to hire an agency to do this, and what does it cost?
You might need an agency if:
- You have a high volume of contacts and need help segmenting, verifying, and deep-cleaning.
- Your ESP makes it difficult to manage list cleaning.
- You need strategy to run re-engagement campaigns before suppressing.
Cost: Agencies typically charge between $500 – $5,000, depending on list size and complexity. Some offer ongoing list management services as part of an email marketing package.