Marketing / Email Marketing

Email list hygiene: what is it and why is it important?

Liz Alton, Sarah Connolly & Jessica Mehring

Updated: Sep 20, 2022 · 10 min read

Toolkit for download in this article

email list cleaning

What is email list hygiene? We’re so glad you asked—because it can make or break your email marketing.

Email hygiene entails cleaning out inactive (cold) email subscribers from your future email marketing campaigns and keeping your remaining list warm with healthy email sending habits. Performing email hygiene regularly will ensure you are only emailing the people who truly want your messages—which also helps you avoid your email being marked as spam.

Email service providers (ESPs) have become smarter and more attuned to what recipients want to receive in their inbox. This means a clean list is a must when it comes to getting your emails delivered to your subscribers’ inboxes. ESPs are digging in deep to the emails you’re sending and the engagement recipients are having with those messages.

Beyond monitoring spam complaints, ESPs are calculating opens, clicks, unsubscribes, inactivity and more into the algorithms that decide inbox placement. Once a recipient opts into your content, it is extremely important for you to monitor and track behavior over time. Permission to send emails does not last forever, even the most engaged subscribers can lose interest as time passes, which can mean they become more of a liability than an asset.

This article will teach you healthy email hygiene habits that will keep your list squeaky clean, keep your small business off of the spam lists, and ensure your marketing emails are delivered and opened. And remember, software such as Keap can help you take your email to the next level.

First things first...

The email terminology every small business owner should get familiar with

What's the worst possible thing that could happen to your email? It gets marked as spam.

OK, but how do you know if you're sending an email that is likely to be marked as spam?

Believe it or not, the health of your email list matters just as much—if not more—than the emails you send. If you have proper email list hygiene habits, and you have a healthy list, your emails are much less likely to be marked as spam because your subscribers are warm and engaged. But what does “warm and engaged” mean, exactly?


In a nutshell, “engagement” is interaction with your email—opens and clicks. From the perspective of an ESP, however, engagement is a bit more technical.

ESPs consider “engagement” as one or more of the following:

Recent opt-ins. These would be email subscribers that have opted into your marketing list, showing a recent interest in your company’s emails. Please note that a recent opt-in could be a false or illegitimate address, so it is important to ensure you’re tracking engagement so you can promptly remove those types of addresses. Another remedy to ensure that a subscriber is who they say they are is implementing the beloved double opt-in (email confirmation) into your marketing campaigns.

Purchasers or subscribers that have been billed within the last 120 days. Purchasing a product or service, or subscribing to your email list isn’t necessarily explicit permission for ongoing email marketing communication, but often (with proper checkboxes and confirmations applied) it renders a higher level of engagement. But just because a subscriber has a valid credit card on file does not necessarily mean they gave you a valid email address. Yet another reason to track engagement.

Opens and clicks in the last 120 days. Once a subscriber is added to your marketing list, these are the two actions you should monitor over time. While opens are an effective metric, clicks are a much more accurate representation of engagement. Why is this? Because if the subscriber opts not to display images when they open your email, or they view the email via the preview pane in their email program, your ESP will not record the open. Just another reason to send highly targeted emails, with a call to action (CTA) to keep your subscribers engaged.

Warm email list

A warm email list is comprised of subscribers who have opted in (given you explicit permission to email them), been contacted in the last four months, and are regularly engaging with your emails.

This sounds simple—but for many small businesses, it’s a real challenge.

Many companies have placed a sign-up box on their website, written a compelling lead gen asset, and collected email addresses. Yet life and business got in the way, and one day they realize they have a growing, but inactive, list. Or they’re regularly sending emails, but engagement—in the form of clicks, opens, and other actions—is low.

Not only is this situation not a good ROI on your time, it can hurt your standing with your ESP—and get you black-listed. You must keep the warmth of your email list at the top of your business priority list.

To drill the point home again—how your ESP views your emails is a big deal. The metrics they use to determine inbox placement is your pot of gold as a sender. It should be a driving force for you to keep the most active and engaged leads in your database.

At Keap, as long as you are sending HTML-based emails, we’re always tracking open and click data. Using our tagging functionality, you can explicitly identify the engaged leads versus the disinterested ones. Tracking the engagement of your leads using tags empowers you to not only identify inactive subscribers but also take action to clean them off your list.

Cold email list

A cold email list is one that hasn’t been contacted for four or more months. If you have sent no email communications to your list in the last four months, you can consider it a cold email list.

Unfortunately, this list of email addresses should not be sent any email communication. Failure to communicate with subscribers upon opt-in is similar to getting a love interest’s phone number and never calling/texting. It’s just bad email etiquette and in a world of immediate response, it will not be received well—by your subscribers or your ESP.

Email list cleaning

Your first step to proper email list hygiene is to ensure that you’re working with a list of email subscribers who want your messages. It’s easier to drive conversions and engagement with clientss who are excited to be in your ecosystem.

Send a re-engagement email that takes one of the following approaches:

  • Asks people who have opened your email in the last six months to click a link and confirm they still want to be on your list
  • Gives list members different subscription options, such as receiving every email or signing up for a digest
  • Confirms that their email address is still current and that they don’t want to update their email preferences

Evaluate cause of death

Your subscribers were probably not dead on arrival. As the list owner, it’s imperative that you evaluate what’s causing the drop-off in interest, so you can fix the problem.

Some common causes of decreased email engagement include:

  • Silence: You left them hungry for content by not sending emails.

  • All sell but no value: You sent out nothing but promotional emails and didn’t create value for your audience.

  • Missing the mark: Your content didn’t resonate with your audience.

  • Overwhelm: Your subscribers get too many messages and yours didn’t stand out.

Get your subscribers to tell you what they want, what they really, really want

Whether you missed the mark during your initial email campaign, or you’re re-engaging after a long absence, it’s important to understand what your audience does want.

Ask them.

Send an email asking your subscribers why they signed up, and what kinds of information, content, and insights you can offer that will make them stick around.

If you want to test specific hypotheses, use a survey.

Or offer personalized 15-minute consultations to 10 people in exchange for them letting you interview them for five minutes.

Conduct research on what your audience wants and what your competitors aren’t providing to find the sweet spot for your message and content. Take a data-driven approach to relaunching your list to ensure you’re on the right track.

Re-engaging a cold email list

If you’re going to reconnect with your list, or just relaunch the way you engage, make it an event. What can you do that delivers massive value and immediately reminds subscribers why it’s good to be in your orbit?

Here are a few email campaign ideas:* Invite subscribers to a Facebook Live event or webinar where you provide exclusive training or answer questions. Send out the recording.* Develop a detailed giveaway, such as a white paper or e-book. Include really valuable material like interviews, templates, or original data that will get readers excited.* Create a multi-part course and use it to nurture your list over the course of a few weeks. Each part of the course can be an email that explores a different element of your business or expertise.

No matter what you send, however:

  • Make it personal
  • Remind them of how they opted in and why they should stay
  • Provide value
  • Follow general email best practices
  • Include a CTA (call-to-action)

Go all out. Don’t hold back. Make your re-engagement offer so interesting and so exciting that it acts as an effective defibrillator to your entire list.

Take Keap's Lifecycle Automation Assessment to identify growth opportunities for your business.

If you’re worried an email won’t be well-received by your cold subscribers, all is not lost. You do have other options for re-engaging them:

  • A phone call
  • Letter or postcard
  • Push notifications
  • SMS
  • Personal one-off email from your own email client
  • Use social media
  • Website pop-up (if subscribers login your site)

How to revive email health and warm up your re-engaged email list

Now that you’ve re-engaged your subscribers, you must commit to maintaining your list going forward, and implement a list hygiene plan so leads never go cold again.

Once you’ve set off a flashbang event that grabs subscribers’ attention, it’s important not to let them down again.

Decide what you can reasonably commit to, and then establish that as the basis of your email strategy. Will you send content daily, weekly, or monthly? Under-commit and over-deliver if possible.

Use your intel on what subscribers really want, and come up with a schedule of content that’s laser-targeted to your audience.

  • Write long form, high-value content your readers will love

  • Experiment with video

  • Curate the best information in your industry

  • Offer subscribers exclusive discounts

Deliver value again and again on a regular schedule until your readers look forward to receiving your emails.

To keep your email list hygiene top-of-mind, print out this infographic and put it on the wall next to the computer you use to write and send marketing emails:

List hygiene infographic

Form healthy email habits now to grow your client base for the long haul

If your email list is currently without a pulse, don’t waste another minute. Assess what’s gone wrong, engage, find out how you can provide value, and then be relentless in your pursuit of building (or re-building) these critical client relationships. Engaging smartly with your list can turn your email into a highly profitable client channel for the long run.

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