This guide is for newsletter publishers and small businesses whose email lists have grown quietly stale. It covers how to define an inactive subscriber, how to run a win-back campaign, how to write a sunset policy, what to do about bounces and spam complaints, and why open rates are a weaker signal than they used to be. It draws on Google’s sender guidelines, Yahoo’s sender best practices and Mailchimp’s help content.
Why a smaller, more engaged list is worth having
Mailbox providers watch how recipients react to your mail. Yahoo’s sender best practices state that mail sent to users who don’t read it, or who report it as spam, harms delivery metrics and sender reputation. Mailchimp makes a similar point: an inactive address still receives your emails but rarely engages, and it often adds to your bounces.
So a list full of people who stopped caring is not a neutral asset. It can drag down delivery for the people who do want your emails. Cleaning is how you protect them.
Step 1: Define “inactive” for your own list
No official source gives one universal definition, so you have to set your own. Mailchimp’s list-cleaning guidance gives “no opens or clicks for 6 months” only as an example of a threshold some platforms use for automatic removal, not as a recommendation. Pick a window that matches how often you send. A weekly newsletter and a quarterly product update need very different windows.
Good inputs for the definition include:
- Clicks, not just opens (see the open-rate section below).
- Other activity Mailchimp suggests considering: purchases, website visits and time on site, and social shares.
- Subscriber age. Mailchimp advises evaluating new subscribers separately from long-term contacts, because new ones have had less chance to engage.
Build the inactive group as a segment in your email service provider (ESP) so it updates itself. If you want ideas for building other segments, see our guide to email list segmentation for small newsletters and businesses.
Step 2: Run a re-engagement (win-back) campaign
Mailchimp recommends running a re-engagement campaign before removing inactive subscribers, and before turning on any automatic removal. Yahoo similarly advises periodically sending reconfirmation emails to inactive subscribers.
A simple sequence looks like this:
- Clean first. Remove addresses that have hard-bounced repeatedly, so you are not re-engaging dead mailboxes.
- Send a short, honest message. Mailchimp suggests a subject line that offers value and invites action, such as confirming interest or updating preferences. One clear button works better than several links.
- Offer a choice. Let people pick a lower frequency or a narrower topic. Mailchimp lists frequency choices and preference updates as ways to prevent negative engagement.
- Follow up once or twice. Mailchimp says to remove contacts who stay inactive after several re-engagement attempts. It does not prescribe an exact number, so decide yours in advance.
- Suppress or archive the silent ones. Move non-responders out of your regular sends.
A common mistake is to disguise the win-back as a big discount or a dramatic “we miss you” message to people who barely remember signing up. A plain permission reminder, which Mailchimp also lists as a way to reduce complaints, is usually more honest and more effective.
Step 3: Write a sunset policy
A sunset policy is a written rule for when you stop emailing people who do not respond. Writing it down stops you from cleaning only when a deliverability problem has already appeared. It does not need to be long. Define these items:
| Decision | What to settle |
|---|---|
| Inactivity window | How long without a click or other activity before someone enters the inactive segment. |
| Win-back attempts | How many re-engagement emails you send, and over how long. |
| Final action | Unsubscribe, suppress or archive non-responders. Keep a record of what you did. |
| Exceptions | New subscribers, customers with recent purchases, or contacts active on your site. |
| Review rhythm | Mailchimp’s guidance suggests a full cleaning every few months as a starting point, adjusted to performance data. |
Check your ESP’s own settings for what “archive” or “unsubscribe” does to your billable contact count and your ability to email the person again. Terms differ between providers.
Step 4: Handle bounces and spam complaints
Bounces
Mailchimp notes that occasional bounces are normal, but a persistent rise suggests more invalid or inactive addresses, and addresses that hard-bounce repeatedly are likely no longer valid and should be removed. Yahoo tells senders to monitor both hard and soft bounces and to remove invalid recipients promptly. Most ESPs suppress hard bounces automatically, but confirm that yours does, especially if you import contacts from another platform. Mailchimp warns that suppression and unsubscribe records do not always sync between platforms, so keep your own master suppression list.
Spam complaints
Google’s sender guidelines say to keep the spam rate in Postmaster Tools below 0.3%, and recommend staying below 0.10% and never reaching 0.30% or higher. Yahoo’s guidance is also to keep your spam rate below 0.3%, and it requires an active Complaint Feedback Loop for all DKIM domains. Yahoo calculates spam rate from mail delivered to the inbox, so your own figures may not match exactly.
To keep complaints low:
- Send only to people who asked for your mail. Google says not to email people who did not sign up and not to buy addresses. Yahoo adds that you should avoid pre-checked opt-in boxes and consider double opt-in.
- Make leaving easy. Google requires one-click unsubscribe for bulk senders’ marketing messages (bulk means more than 5,000 messages a day to Gmail accounts), plus a visible unsubscribe link in the body. Yahoo says to process requests within 2 days and not to require a login.
- Honor the frequency people signed up for. Yahoo gives the example of not sending daily mail to a weekly list.
A good welcome flow sets expectations early and reduces forgotten sign-ups; see our post on building an email welcome sequence. For the technical authentication that Google requires of bulk senders, we already cover the setup in SPF, DKIM and DMARC for newsletter senders, so it is not repeated here.
Why open rates are an unreliable signal
If you define inactivity by opens alone, you will misclassify people. Apple Mail Privacy Protection (MPP), released with iOS 15 and macOS Monterey in 2021, causes Apple Mail to preload tracking pixels. According to Mailchimp’s FAQ, emails in Apple Mail are then recorded as opened regardless of what the contact did, which inflates open rates.
That has practical consequences for list cleaning:
- Apple Mail users can look engaged when they are not, so they may never reach your inactive segment.
- Resends to “did not open” will not reach contacts with MPP enabled. Mailchimp recommends resending to “did not click” instead.
- Automations triggered by opens may reach a larger audience than intended, and “not open” triggers a smaller one.
Mailchimp points to clicks, bounces, unsubscribes, conversions and purchase data as more dependable measures, and notes that dashboards can exclude MPP-affected opens for emails sent on or after June 22, 2024. Other ESPs handle this differently, so check how yours reports opens before you build a segment on them.
Common mistakes
- Deleting inactive contacts without a win-back attempt.
- Using opens as the only activity signal.
- Treating new subscribers the same as long-term ones.
- Re-importing a purged list from an old backup.
- Cleaning once after a deliverability scare and never again.
Key takeaways
- Define inactivity yourself, using clicks and other activity, not opens alone.
- Run a win-back campaign before removing anyone, then act on non-responders.
- Write a sunset policy so cleaning happens on a schedule.
- Remove repeat hard bounces and keep spam complaints under Google’s and Yahoo’s 0.3% line, aiming lower.
- Treat open rates with caution because of Apple Mail Privacy Protection.
FAQ
How often should I clean my email list?
Mailchimp’s guidance suggests a full cleaning every few months as a starting point, then adjusting based on performance data. Remove hard bounces continuously.
How long until a subscriber counts as inactive?
There is no official figure. Mailchimp cites six months without opens or clicks only as an example of an auto-removal threshold. Choose a window based on how often you send.
Is a spam rate above 0.3% a problem?
Both Google and Yahoo tell senders to keep it below 0.3%. Google adds that it recommends staying under 0.10%.
Can I trust open rates at all?
Use them cautiously. Apple Mail Privacy Protection can record opens that did not happen, so rely on clicks, conversions and other actions when judging engagement.