A sunset policy is a written rule for when you stop emailing subscribers who have not engaged for a set period, after first giving them a chance to re-engage. It keeps your list made up of people who actually want to hear from you.
How a sunset policy works
A typical policy has three parts:
- A definition of inactive. For example, no click, purchase, reply or website visit in the last 180 days. The right window depends on how often you send and how long your buying cycle is: a coffee subscription might use three months, while a kitchen fitter whose customers buy once a decade might use eighteen.
- A last attempt. Inactive subscribers receive a short re-engagement campaign, often two or three emails, asking whether they still want to hear from you.
- An action. Anyone who still does not engage is moved off the active list, usually onto a suppression list so they are not mailed again, or onto a much lower sending frequency.
Most email platforms can build the inactive segment automatically and run the whole process as an automation, so it happens continuously rather than as a once-a-year clear-out.
Why it matters
Mailbox providers watch how recipients treat your emails. A large group who never open or click tells them your mail is unwanted, which pulls down your sender reputation and affects delivery to everyone, including your best customers. Long-abandoned addresses are also where recycled spam traps appear.
There is a cost argument too. Many email platforms price by the number of contacts, so you may be paying every month to email people who stopped reading years ago.
In the UK, a sunset policy also supports the storage-limitation principle in UK GDPR, which says personal data should not be kept longer than you need it. Holding marketing data on someone who has shown no interest for years is hard to justify, and a documented policy shows you have thought about it.
Common mistakes
- Defining inactivity by opens alone. Apple Mail Privacy Protection records automatic opens, so many inactive subscribers look active. Use clicks, purchases and site activity where you can.
- Setting the window too short. Cutting people who have been quiet for a few weeks loses customers who buy seasonally.
- Skipping the last attempt. Some quiet subscribers do still want your emails. Ask before you remove them.
- Deleting instead of suppressing. If you delete addresses entirely, a later import can add them straight back. Keep minimal suppression details instead.
- Ignoring recent customers. Someone who bought last month but never clicks an email is not inactive. Include purchase data in the definition.
How to act on it
Use your own data to set the window. Find how long typically passes between a customer’s purchases or enquiries, and set the inactivity threshold comfortably beyond that. Write the policy down in a few sentences, covering what counts as engagement and what happens at the end.
Build the inactive segment, write a short re-engagement sequence, and automate the move to suppression for anyone who does not respond. Review the numbers each quarter: how many people enter the flow, how many come back, and whether your delivery figures improve.
A sunset policy is one of the habits of good list hygiene I put in place as part of digital marketing strategy and consulting work.