Email list cleaning: how to sunset inactive subscribers

Why email list cleaning matters#

Email list cleaning means removing addresses that no longer work and, harder, deciding when to stop mailing people who still receive your email but no longer want it. The second part is a sunset policy: a rule that moves subscribers who have gone quiet through a last attempt to win them back, and then stops mailing them.

The mailbox providers ask for it directly. Google’s sender guidelines say: “Consider unsubscribing recipients who don’t open or read your messages,” and “Periodically send messages to confirm that recipients want to stay subscribed.”^[1] Yahoo tells senders to “Monitor hard and soft bounces as well as inactive recipients” and to consider “sending a reconfirmation email to inactive subscribers periodically.”^[2]

What happens to a list nobody cleans#

• Complaints rise. People who forgot they signed up report the email as spam. Google asks bulk senders to keep the spam rate below 0.10% and never reach 0.30%,^[1] and Yahoo sets 0.3% as its line.^[2]
• Mailboxes close. A Yahoo mailbox not accessed for 12 months “stops receiving new emails” and its contents are deleted,^[3] and Google may delete a personal account “that has not been used within a 2-year period”.^[4] Mail to either bounces.
• Abandoned addresses become traps. Spamhaus and Validity describe recycled spam traps as “email addresses that were once valid but are now no longer used”, and point to lists with “no sunset policy, poor bounce management” as the way they get in.^[5] A spam trap never opens or clicks, so it looks exactly like an inactive subscriber.

M3AAWG’s definition of a “dirty mailing list” includes addresses that “have not been kept up-to-date over time”, for example through poor handling of bounces or unsubscribes “and/or not mailing to the addresses in a year or more”.^[6] All of this lands on your sender reputation, which decides where the mail to your engaged subscribers goes too.

How to define an inactive subscriber#

No mailbox provider publishes a number of days after which a subscriber counts as inactive, and no study we found establishes one. The definition is yours, and it should follow from two things: which signals you can trust, and how often you send.

Use signals a person has to cause#

Rank the signals by how certain it is that a human did something. From strongest to weakest:

1. Activity in your product or shop: a login, a purchase, a reply. These happen outside email and cannot be faked by a mail client.
2. Clicks: a tracked click means someone followed a link. Security scanners can click too, so a click seconds after delivery on every link is worth discounting.
3. Opens from clients that do not preload: still meaningful, if you can tell them apart.
4. Opens in general: the weakest signal since 2021, for the reason in the next section.

Scale the window to how often you send#

A window only makes sense in sends, not days: someone who has had four emails and clicked none is different from someone who has had forty. Pick a window that gives a real subscriber several chances to act. As outer bounds, M3AAWG treats not mailing an address for a year or more as a mark of a dirty list,^[6] and for consent-based marketing the UK regulator suggests, if in doubt, you “consider refreshing consent every two years”.^[7]

Why opens can’t tell you who is inactive#

In June 2021 Apple announced Mail Privacy Protection, which “helps users prevent senders from knowing when they open an email, and masks their IP address”.^[8] Apple’s privacy documentation explains how: Mail “downloads remote content in the background by default — regardless of whether you engage with the email”.^[9] An open pixel is remote content, so it fires whether or not the person ever looked.

The consequence for list cleaning is two-sided. A subscriber who uses Apple Mail with the feature on may “open” every email and never read one, so an open-based rule keeps them forever. And a rule that says “no opens in 90 days” quietly exempts much of your list. Litmus put it bluntly when the feature shipped: any segmentation “based on the last open date are near useless—especially critical for purging unengaged contacts.”^[11]

Segment your list by engagement#

Before you remove anyone, sort everyone. The windows below are an example for a list that gets one email a week; adjust them to your frequency. They are a starting point we suggest, not a published standard.

Bounces are the one category with a published rule of thumb. M3AAWG recommends removing an address “if it bounces consecutively at least two times over two weeks or more”, which allows for a temporary fault on the receiving side.^[6] A hard bounce that says the mailbox does not exist needs no second try; see hard bounce vs soft bounce.

Run a re-engagement campaign before you sunset#

A re-engagement (or win-back) campaign asks the inactive segment one question: do you still want this? It is what Google means by periodically confirming that recipients want to stay subscribed.^[1] The example below is ours, not a tested formula; two or three emails over two to three weeks is common practice.

• Make staying one click. The “keep me subscribed” link is the signal you act on, so it must be a tracked link, not a reply you have to read by hand.
• Offer less, not only nothing. A preference choice keeps people who wanted fewer emails rather than none.
• Write subject lines that say what is happening. “Should we keep emailing you?” is clearer than a discount dressed up as news, and CAN-SPAM forbids deceptive subject lines anyway.^[12]
• Keep the unsubscribe link visible. An inactive subscriber who leaves is a success. One who hits “report spam” is the outcome this whole process exists to avoid.

That benchmark measures lapsed customers in ecommerce, not newsletter readers, but the lesson carries: most of the inactive segment will not come back. Plan for the sunset, and count anyone who returns as a bonus.

Sunset: stop mailing the ones who don’t respond#

Anyone who finishes the re-engagement flow without a click leaves your regular mailings. That is the sunset. In practice it means:

1. Stop marketing to them. Opt them out of the lists or topics your campaigns go to, or add them to a suppression list.
2. Keep transactional mail flowing. A customer who ignores your newsletter still needs their receipts and password resets. The sunset applies to marketing.
3. Record why. Store the date and the reason (“sunset after re-engagement”), so a later import cannot quietly put them back.
4. Let them return on their own. If they sign up again, that is fresh consent; welcome them as new. The welcome email guide covers that first message.

Suppression vs deletion, and GDPR erasure#

Sunsetting someone and deleting them are different acts, and doing the second when you meant the first is how people who opted out end up mailed again after the next import.

The UK Information Commissioner’s Office recommends suppression for people who object to marketing. The right to object to direct marketing “is an absolute right”, but it “does not automatically mean that you need to erase the individual’s personal data, and in most cases it will be preferable to suppress their details.”^[14] Suppression means “keeping just enough information about someone to ensure you respect their preferences in the future, so you must not keep more than you need”.^[15]

When someone asks to be erased#

An erasure request is different from an unsubscribe. The ICO lists objecting to direct marketing among the cases where the right to erasure applies, and you must respond “without undue delay and at the latest within one month”.^[16] The nuance is the suppression list itself: “Because we don’t consider that a suppression list is used for direct marketing purposes, there is no automatic right for people to have their information on such a list deleted.”^[15] So the usual answer to an erasure request from a subscriber is to delete their profile, history and properties, and keep only the address (or a hash of it) on the suppression list, telling them that you have done so and why.

Step by step: clean your list and sunset inactive subscribers#

The first two steps remove addresses that cannot receive mail; the rest handle the people who can but do not engage.

1. 1

   Suppress what cannot be delivered

   Suppress hard bounces and spam complaints as they arrive, and remove addresses that bounce at least twice in a row over two weeks or more, as M3AAWG recommends.

2. 2

   Define inactive with signals a person causes

   Use clicks, purchases, logins and replies. Treat opens as a weak signal, because Apple Mail Privacy Protection loads images whether or not the reader engages.

3. 3

   Set the window in sends, and write it down

   Choose a window that gives a real subscriber several chances to act at your sending frequency, then segment the list into active, lapsing and inactive.

4. 4

   Run a re-engagement flow

   Send the inactive segment two or three emails over two to three weeks asking whether they still want your mail, with a one-click way to stay and an option to get less.

5. 5

   Sunset everyone who does not respond

   Stop sending them marketing mail by opting them out of your lists or topics or suppressing the address, keep their transactional mail flowing, and record the date and reason.

6. 6

   Suppress, don't delete, and run it every week

   Keep opted-out and sunset addresses on a suppression list so an import cannot add them back, delete profiles only for erasure requests, and run the rule continuously.

Doing it in Rasket#

Bounces and complaints add rows to your suppression list automatically, and every send (transactional, campaign or automation) is checked against it; the details are in the suppression list explained. Every campaign carries one-click unsubscribe headers, so the people who want to leave can.

Rasket’s segments filter on contact fields, your own contact properties and topic subscriptions, not on engagement history directly. So your code decides who is lapsed, using the click events from delivery webhooks and your own product data, and sets a property such as lapsed = true. A segment filtered on that property collects them, and an automation that starts when a contact enters the segment runs the re-engagement emails: send steps, delays, and a condition on a property your code sets when they click “keep me subscribed”. Its last step can opt the contact out of your newsletter topic. See Automations and Campaigns.

Deleting a contact in Rasket erases its profile and memberships; the suppression list is kept separately, by address, so an erased contact who unsubscribed from everything, or bounced or complained, stays suppressed.

Email list cleaning myths and facts#

• Documented by Google “A bigger list is always better for deliverability.” False. Google asks senders to consider unsubscribing people who do not engage.^[1]
• Measured in research “No opens in 90 days means inactive.” Unreliable: Mail Privacy Protection loads content regardless of engagement, and Apple clients account for most tracked opens.^[9][10]
• Unproven “There is a standard inactivity window.” No provider publishes one. Choose yours from your send frequency.
• Unproven “Deleting unsubscribers is the privacy-friendly choice.” Usually the opposite: the ICO says suppression is preferable, so their preference is respected if the address comes back.^[14]
• Unproven “A verification service makes a list clean.” It can find addresses that do not exist. It cannot tell you who wants your email, and a recycled trap is a working address.^[5]

The rules that apply whatever you decide#

In the United States, CAN-SPAM requires opt-outs to be honoured within 10 business days, and once people have opted out “you can’t sell or transfer their email addresses, even in the form of a mailing list”.^[12] Yahoo requires senders to “honor unsubscribes within 2 days”.^[2] In the UK, the ICO’s guidance above governs what you keep and for how long, and its consent guidance suggests refreshing consent every two years if in doubt.^[7]