SMS is the most intrusive channel you own. Use it for time-sensitive, behavior-triggered moments, keep it compliant, and it becomes the highest-converting line you have. Treat it as a second email list and you'll torch deliverability and run up real legal exposure.
I see a lot of brands bolt SMS on because a competitor did, then blast it like email and wonder why opt-outs spike. SMS works on different physics. It lands on a lock screen next to texts from someone's mother, so the bar for "worth interrupting them" is much higher, and so is the cost per send. The question is never "should we do SMS." It's "which exact moments earn a text."
The filter I use: a message earns SMS when it's time-sensitive and triggered by something the customer just did. Email is the patient channel for stories, education, and the long nurture. SMS is for "this is happening now and it expires."
Three things separate SMS from email, and each one should change how you use it:
Build the SMS list as its own asset with its own explicit consent. Don't assume an email subscriber wants texts, and don't migrate one list into the other. They're separate channels with separate legal requirements.
The gap between triggered and broadcast SMS is the whole argument for being selective:
| Metric | Automated SMS flows | Broadcast SMS |
|---|---|---|
| Share of SMS revenue | ~45.2% | the remainder |
| Share of sends | ~7.6% | the remainder |
| Click-to-conversion rate | ~3.81% | ~0.97% |
Behavior-triggered SMS pulls roughly 45% of revenue from under 8% of sends, and converts about 4x better than broadcasts. Source (2025, directional): Omnisend SMS statistics — https://www.omnisend.com/blog/sms-marketing-statistics/ and Omnisend SMS conversion rate — https://www.omnisend.com/blog/sms-marketing-conversion-rate/ . Caveat: SMS benchmarks swing hard by list quality and message type, and vendor data skews optimistic. Verify against your own send data.
One number worth building your timing around: sending within roughly 5 minutes of a customer action has been reported to lift click-through to about 36%, against a ~9.2% average. Same Omnisend source, 2025, directional, verify. That's the case for tight automation triggers over a human hitting "send" twice a day.
Start at the top. Add the next one only once the one above is dialed in and your consent volume justifies it. This ordering is my own operator guidance, not a benchmark.
| # | Use case | Why it earns a text | Shape of the message |
|---|---|---|---|
| 1 | Abandonment (cart / checkout) | Highest intent, time-sensitive, recoverable revenue. The send-within-5-minutes effect lives here. | One message, the item, one link back. No essay. |
| 2 | Transactional / shipping | Order and shipping updates get the warmest reception of anything you send, and they build the trust that earns future marketing texts. | Status plus tracking link. Genuinely useful, never promotional. |
| 3 | Back-in-stock / price-drop / drop launches | Scarcity and urgency are where SMS fits best. "It's back and it sells fast" is exactly the lock-screen-worthy message. | The product, the urgency, one link. |
| 4 | VIP / replenishment reminders | For your most engaged, consent-rich segment only. Reorder nudges and early access, not list-wide blasts. | Personalized, timed to the trigger (run-out date, drop date). |
Notice what's not on this list: daily promo blasts, newsletter forwards, "just checking in." If a message isn't time-sensitive and triggered, it probably belongs in email.
The order matters because cases 1 and 2 carry almost no opt-out risk. They're useful and expected, and they warm the relationship so that when you do send cases 3 and 4, people don't bail. Lead with utility, earn the right to sell.