An email sunset policy is a set of rules that automatically stops sending to subscribers who have not opened or clicked within a defined window. It protects sender reputation by suppressing dormant contacts before they hurt inbox placement. Most senders sunset after 90 to 180 days of no engagement.
Why sunsetting inactive subscribers matters
Mailbox providers grade you on engagement. Gmail, Outlook, and Yahoo watch opens, clicks, replies, and how often people delete your mail without reading it. When a large share of your list never engages, those signals tell the filters that your mail is unwanted. Inbox placement then falls for everyone on the list, including the subscribers who still want to hear from you.
Dormant contacts hurt you in three ways. They drag down your sender reputation. They inflate your list size and your monthly bill. And the oldest ones go fully abandoned, get reclaimed by the provider, and can turn into recycled spam traps. A sunset policy stops all three problems before they compound into a deliverability crisis.
The math is simple. A list of 100,000 addresses where only 10,000 open is worse than a list of 15,000 addresses where 9,000 open. The smaller, engaged list lands in the inbox. The bloated one gets filtered. Fewer, more engaged subscribers almost always beat a big roster of ghosts.
What is a re-engagement window?
A re-engagement window is the period of inactivity you allow before treating a subscriber as at risk. It starts at the last open, click, or purchase. Common windows run 90, 120, or 180 days depending on how often you send. Daily senders sunset faster than monthly senders.
Match the window to your cadence. If you send daily, 30 days of silence is already a strong signal, so you can act quickly. If you send monthly, one missed email means almost nothing, and you should wait far longer before flagging anyone. The table below gives sensible starting points for each send frequency. Treat them as a baseline and tune against your own numbers.
| Send frequency | Flag as dormant | Start re-engagement | Suppress for good |
|---|---|---|---|
| Daily | 30 days no engagement | 45 days | 60 days |
| Weekly | 60 days | 90 days | 120 days |
| Monthly | 120 days | 150 days | 180 days |
| Quarterly | 180 days | 240 days | 270 days |
These thresholds are defaults, not rules handed down from on high. Apple Mail Privacy Protection inflates opens for a big slice of your list, so do not trust opens alone. Lean on clicks, replies, form fills, and site visits as harder proof that a human is still paying attention.
How to build a re-engagement campaign
Before you suppress anyone, give them a clear chance to stay. A re-engagement campaign is a short, honest sequence aimed only at contacts who crossed your dormancy line but have not hit the suppression threshold. Keep it to two or three emails across a week or two. Do not drag it out for a month.
- Build a segment of contacts who crossed your dormancy threshold but have not yet reached the suppression line.
- Send a short win-back email that asks one clear question: do you still want these emails?
- Wait a few days, then send a second reminder with a one-click way to stay or leave.
- Give them a reason to stay, such as a useful resource, a discount, or a lighter sending cadence.
- Measure engagement on this campaign only, using clicks and replies rather than opens.
- Move anyone who engages back to your active list and suppress everyone who does not.
Judge the campaign on its own opens and clicks, not on lifetime history. A contact who clicks once here has told you they still want in, so move them back to active. Everyone who stays silent has answered you just as clearly.
When should you suppress dormant contacts for good?
Suppress a contact for good once they ignore your full re-engagement sequence and pass the suppression threshold for your send frequency. For most senders that means no opens or clicks in 180 days plus a failed win-back campaign. Suppression is not deletion. Keep the record, just stop mailing it.
Suppression means adding the address to a do-not-mail list inside your platform. The record stays for reporting and compliance, but every future campaign skips it. Never simply delete the row. If you delete an address and later re-import it from another source, you lose the history that told you to stop sending, and you risk mailing a recycled spam trap all over again. Suppression is a memory. Keep it.
Do not feel guilty about it. A subscriber who has ignored 180 days of email and a direct win-back is not your audience anymore. Continuing to mail them only teaches spam filters to distrust you. Letting them go is how you protect delivery to the people who still open, click, and buy.
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Verify your list before you sunset it
Low engagement is not always disinterest. Sometimes the address simply broke. People change jobs, close old accounts, and abandon inboxes they no longer check. Those addresses hard bounce or quietly fail, and in an open report they look identical to a living human who just ignored you. Verification separates the two so you act on facts.
Run your dormant segment through a verifier before you write anyone off. Our free email verifier flags invalid mailboxes, catch-all domains, role addresses like info@ and sales@, and known disposable providers, then runs MX and SMTP-level checks so you can see which addresses are still able to receive mail. Anything that comes back invalid should be suppressed at once, with no win-back attempt. The CSV is parsed in your browser and never uploaded, so your list stays private.
Verification also protects the win-back itself. Sending a re-engagement blast to a segment full of dead addresses spikes your bounce rate at the worst possible moment. Clean first, then mail the survivors.
Common sunset policy mistakes to avoid
The most common mistake is suppressing on opens alone. Since Apple started pre-loading images, opens are noisy, and you will retire people who are actually reading. A second mistake is skipping the win-back email and cutting contacts cold, which throws away subscribers who would have clicked if asked. A third is deleting instead of suppressing, which erases your own paper trail.
One more trap: setting the policy once and forgetting it. Your send frequency changes, your audience changes, and your thresholds should follow. Review them every quarter against your bounce rate, complaint rate, and inbox placement, then adjust the windows up or down.
Finally, watch for over-suppression. If your thresholds are too aggressive, you will retire warm leads who buy on a slow cycle. Balance protection with patience, and always verify before you cut.
Turn your sunset policy into a routine
Write the policy down and let automation enforce it. Define your dormancy threshold, your re-engagement trigger, and your suppression line for each send frequency, then build segments that update themselves so contacts move through the stages without manual work. Run dormant addresses through the free email verifier on the way through, and keep your suppression list permanent. A written, automated sunset policy keeps your list small, engaged, and trusted, which protects the people who genuinely want your email. If cleaning and rebuilding pipeline by hand is eating your week, Synthisia can handle done-for-you lead generation while you keep your sending healthy.