An SMS sunset flow is a short sequence of 1–2 messages sent to unengaged subscribers giving them a clear off-ramp before you suppress or remove them from your active list. Done right, it protects your deliverability, lowers your per-send cost, and ensures every future message you send reaches someone who actually wants it.
Done wrong — or skipped entirely — inactive subscribers drag down open rates, inflate costs, and trigger carrier spam flags that affect your entire sending reputation.
Why SMS List Hygiene Matters More Than Email
With email, inactive subscribers cost you little beyond a slightly higher unsubscribe rate. With SMS, the consequences are sharper:
Per-message cost. Every SMS costs $0.01–$0.02. Sending to 5,000 subscribers who never open costs $50–$100 per broadcast — money spent on zero ROI.
Carrier spam thresholds. Carriers monitor opt-out rates and spam complaints. An inactive segment that finally opts out in bulk after months of ignored messages can spike your opt-out rate above carrier tolerance limits and trigger sending restrictions.
Engagement rate dilution. Low engagement depresses your program-level analytics, making it harder to identify real performance problems.
For the re-engagement step before sunsetting, start with an SMS winback campaign — subscribers who don’t respond to winback are your sunset candidates.
When to Trigger the Sunset Flow
Define “inactive” for your store before setting up the flow. The standard benchmark is 90–120 days of zero engagement (no opens, no clicks, no replies, no purchases attributed to SMS).
Segment criteria for sunset trigger: – No click on any SMS in the past 90 days – No reply to any SMS in the past 90 days – No SMS-attributed purchase in the past 90 days – Has already been through a winback sequence without converting
Do not sunset subscribers who have never clicked but have recently purchased through other channels. A subscriber who buys regularly but ignores your texts is still a valuable customer — they just may not be an SMS buyer. Suppress them from broadcast sends instead.
The Sunset Sequence
Message 1: The Gentle Check-In Keep this low-pressure. No offer. The goal is to see if there is any residual interest before you close the door.
Hey [Name] — it’s been a while since we’ve heard from you. Are you still interested in hearing from [Brand] via text? If yes, just reply YES. If not, no worries — just reply STOP and we’ll remove you. Either way, thanks for being here.
Message 2 (5–7 days later, if no response): The Final Notice Make the off-ramp easy and the consequence clear.
[Name] — this is your last message from [Brand] unless you’d like to stay. No action needed to keep hearing from us. Reply STOP to opt out permanently. We’ll take your silence as a “keep me subscribed” — but we won’t message you often.
After Message 2, suppress the subscriber from all broadcast sends regardless of response. Only re-enter them into flows if they make a purchase or actively re-engage.
Suppression vs. Deletion: What to Do With Sunset Subscribers
Suppression (recommended): Remove them from active sending lists but keep their record in your SMS platform. They remain opted-in technically, which means if they purchase again or click a link that re-triggers an automated flow, they’ll receive that message. This preserves the opt-in relationship without actively spamming them.
Deletion: Permanently removes the contact. Do this only for subscribers who explicitly replied STOP, or for numbers that have bounced or returned carrier errors. Deleting opted-in contacts who simply went quiet is aggressive and non-reversible.
How Often to Run the Sunset Flow
Build sunset as an always-on automated flow, not a one-time clean. New subscribers who go inactive over time should automatically enter the sunset sequence when they hit your inactivity threshold.
Setup in your SMS platform: – Trigger: Subscriber has been active for 90+ days with zero click/reply/purchase engagement in that window – Exclude: Subscribers currently in an active winback sequence (let that finish first) – Exclude: VIP or high-LTV customers (run a separate re-engagement flow with a stronger offer)
Benchmarks: What to Expect After a Sunset Clean
A well-executed sunset typically removes 10–25% of a mature SMS list. What improves after:
| Metric | Change After Sunset |
|---|---|
| Click-through rate | +15–30% lift (cleaner list, higher relative engagement) |
| Opt-out rate per send | Decreases significantly |
| Cost per send | Drops proportionally to list reduction |
| Carrier spam flags | Reduced, improving deliverability overall |
The short-term revenue dip from sending to fewer people is offset by better per-send performance and lower costs.
FAQ
What is an SMS sunset flow?
An SMS sunset flow is a 1–2 message sequence sent to unengaged subscribers giving them the chance to confirm they want to keep receiving texts, or opt out. Subscribers who do not respond are suppressed from future broadcast sends. It protects deliverability, reduces per-send cost, and keeps your active list engaged.
When should you sunset SMS subscribers?
Trigger the sunset flow after 90–120 days of zero engagement — no clicks, no replies, no SMS-attributed purchases — and only after a winback sequence has already been attempted without success. Subscribers who have purchased through other channels recently should be suppressed from broadcasts but not sunset.
Does removing subscribers hurt my SMS program?
Short term, your list size drops. Long term, your program performs better on every metric that matters: CTR, conversion rate, cost per recovery, and carrier deliverability. Sending to 3,000 engaged subscribers outperforms sending to 10,000 mixed ones every time.
