Re-engagement campaigns and sunset policies

A sunset policy is a rule for when you stop mailing subscribers who no longer engage, and a re-engagement campaign is the last attempt to win them back before you do. Both exist because long-inactive addresses are where the damage hides: abandoned mailboxes start to bounce, and some are later turned into recycled spam traps. Define inactivity by clicks, replies, purchases and logins rather than opens, which Apple Mail Privacy Protection made unreliable. Verify an old segment before you mail it, ask once whether people still want your mail, and suppress everyone who does not answer.

Why inactive addresses are a risk

An address that nobody reads does more than lower your open rate. Three things happen to it over time.

• It may stop existing. People change jobs and abandon free mailboxes. Mail to a deleted mailbox comes back as a hard bounce such as 550 5.1.1. M3AAWG's Sender Best Common Practices (section 2.2) notes that receivers use the volume of such permanent failures to judge a sender.
• It may become a trap. M3AAWG's Help! I Hit a Spam Trap! describes recycled traps: addresses that once belonged to a person, were retired after a period of inactivity, and now record who still mails them. Operators choose their own waiting period; M3AAWG suggests 12 months as a minimum. It links a recycled trap hit to poor list management (or a very old list), missing bounce processing, or both. More in spam traps.
• It drags down your engagement. Yahoo's sender best practices say that mailing people who do not read your messages harms your delivery metrics and reputation.

Spamhaus makes the link explicit in its sender guidelines: old inactive addresses are where recycled traps sit, and senders should adopt a sunset policy that removes addresses that no longer engage. M3AAWG's Sender Best Common Practices (version 4.0, appendix C) counts a list whose addresses have not been mailed in a year or more among the signs of a dirty mailing list.

What mailbox providers say

None of the large providers publishes an inactivity deadline, but all of them point the same way.

Sources: Google's email sender guidelines, Yahoo's sender best practices, Microsoft's requirements for high-volume senders (April 2025) and the Outlook.com postmaster policies. Platforms say the same. Mailchimp's audience requirements warn that permission can go stale when you do not actively engage with contacts.

Define inactivity without trusting opens

Opens were the classic signal, and they no longer mean much. Apple's Mail Privacy Protection page explains that Mail downloads remote content in the background by default, whether or not the person engages with the message, and routes it through two relays that hide the reader's IP address. A tracking pixel in a message that was never read can still load, so an "open" from an Apple Mail user tells you little. Google's sender guidelines add that Gmail does not track open rates, and that low open rates are not necessarily a sign of a deliverability problem.

Build your definition on signals a background download cannot fake:

• clicks on links in your messages;
• replies;
• purchases, bookings or other conversions;
• logins or activity on your site or app;
• visits to the preference center, or a changed preference.

Count from the last such signal, not from the sign-up date. A new subscriber who has not clicked yet is not inactive; give each address time to receive several messages before it can fall into a lapsed segment. Treat an open as a weak hint at most: it can confirm that a click-less subscriber still exists, but it should not keep an address on your list for years.

Segment by last engagement

Choose the windows from your own sending frequency and buying cycle. A daily newsletter and a yearly renewal reminder cannot share one number, and no provider publishes one. What matters is that every address falls into exactly one bucket and moves down as time passes.

Set the inactive cut-off well inside M3AAWG's 12-month minimum for trap conversion, so a dormant address leaves your list before it can turn into a recycled trap.

A re-permission sequence

A win-back sequence is short and asks one clear question. A pattern that works for most lists:

1. Clean the segment first. Verify the addresses and remove those whose action is remove (see below). Mailing a dormant segment unverified is exactly how hard bounces and recycled traps arrive in one go.
2. Remind them who you are. The first message says why the person is receiving it, when they signed up if you know, and what they get by staying. Keep the confirm button prominent.
3. Offer a lighter option. Many people leave because of volume. Link a preference center where they can choose fewer messages or only some topics.
4. Ask a final time. The last message says plainly that you will stop writing unless they confirm. Anyone who does not click is suppressed when the sequence ends.

Make leaving easy at every step. A visible unsubscribe link and a working one-click List-Unsubscribe header cost you an address; a spam report costs you reputation.

Send the sequence as its own stream, separate from your main campaigns, at a modest volume. Spamhaus asks senders not to mail old, unengaged addresses while they warm up a new IP or domain, so never run a win-back on fresh infrastructure. Watch bounces and the spam rate in Google Postmaster Tools and your feedback loops while it runs, and stop if either jumps.

When to suppress

Suppress, do not just delete: keep the address on a suppression list so a later import or a sync with another tool cannot add it back. Spamhaus warns against moving to new sending infrastructure without carrying the suppression list across. Suppress:

• Unanswered re-permission. Everyone who completed the sequence without confirming.
• Hard bounces, at once. Spamhaus asks for immediate suppression. See bounce processing.
• Repeated soft bounces. M3AAWG's Sender Best Common Practices (section 2.2) generally considers it best practice to remove an address that bounces at least two times in a row over two weeks or more.
• Complaints and unsubscribes, as soon as they arrive.

M3AAWG's spam trap paper adds two points worth building into the policy. If trap hits continue, make the suppression rule somewhat more aggressive. And take special care when a change in segmentation sends mail to people you have not mailed for an extended time, because those addresses may have been retired and repurposed in the meantime.

Verify before re-mailing old segments

Verification answers one question: does this mailbox accept mail today? It helps you find the dead and dangerous addresses before they bounce or trigger a trap. For an old segment:

• invalid results, such as no_mailbox, have the action remove. These are the abandoned mailboxes that would bounce.
• Some valid results carry a warning reason and the action remove, such as spamtrap, trap_pattern or suppressed. Follow the action, not the status.
• low_engagement marks a working mailbox that its owner seldom reads; the action is send_with_caution, a good fit for the re-permission sequence rather than your regular campaigns.
• catch_all and unknown results cannot confirm the mailbox. Put them at the end of the sequence, in small batches.

Be clear about the limits. A working recycled trap accepts mail like any mailbox, so a check cannot find every one. Spamhaus says list validation does not clean out traps and is no replacement for permission. Verification tells you an address works, not that its owner still wants your mail. That is the re-permission sequence's job, so use both. For a full routine, see email list cleaning.

Questions

How long before a subscriber counts as inactive?

There is no published standard; it depends on how often you send and how often people buy. The fixed point is the risk: M3AAWG suggests trap operators wait at least 12 months before reusing an abandoned address, so your sunset rule should remove dormant addresses well before that.

Should Apple Mail opens keep someone on my list?

Not on their own. Apple says Mail Privacy Protection downloads remote content whether or not the person engages, so an open from an Apple Mail user may not be a read. Look for a click, reply, purchase or login.

Can I mail suppressed subscribers again later?

Only if they come back by themselves, for example by signing up again or confirming through a new double opt-in. Re-adding a suppressed segment in bulk undoes the policy.

Try it

Upload a dormant segment to bulk email verification and remove the rows whose action is remove before the first win-back message, or check a single address in the free email checker.

Related

• Statuses, actions and reasons.
• Glossary: list hygiene.
• Bounce code 550 5.1.1.

Related guides

• Spam traps explained
• How to clean an email list
• Sender reputation explained
• One-click unsubscribe and the List-Unsubscribe header
• Double opt-in (confirmed opt-in)
• All guides

Sources

• M3AAWG: Help! I Hit a Spam Trap! (February 2023): recycled traps, the 12-month minimum, suppressing chronically unengaged recipients, care with long-unmailed segments.
• M3AAWG: Sender Best Common Practices, version 4.0 (August 2026): section 2.2 on removing repeatedly bouncing addresses, appendix C on dirty mailing lists.
• Spamhaus: Sender guidelines: sunset policy, old inactive addresses and recycled traps, hard bounce suppression, suppression lists, limits of list validation.
• Apple: Mail Privacy Protection and privacy: background download of remote content and IP relays.
• Google: Email sender guidelines: unsubscribing non-readers, periodic confirmation, open rates.
• Yahoo: Sender best practices: inactive recipients and reconfirmation.
• Microsoft: Outlook's new requirements for high-volume senders (April 2025): removing inactive or invalid addresses regularly.
• Microsoft: Outlook.com postmaster policies: stopping after repeated non-delivery reports.
• Mailchimp: Requirements and best practices for audiences: stale permission.

How we wrote this: drafted by the email-validation.org team with the help of AI writing tools, from our product documentation and the sources linked in the text.