Consent for SMS Marketing: Text Messages Are Not Small Emails
A text message lands differently from an email. It interrupts on a personal device, it can cost the recipient money in some markets, and regulators treat the channel accordingly. Brands still routinely import numbers collected for shipping updates into marketing programs and discover the rules in the most expensive way possible.
This guide covers SMS consent properly: what a valid opt in looks like, why the number source matters, frequency and quiet hours, and the opt out discipline that has to work instantly and across every tool you send from.
One channel, one consent
Email permission does not extend to texts, and a checkout checkbox for order updates does not extend to promotions. Each signup, whether by keyword, web form, or paper, should state that the person is joining a marketing text program, name the brand, give an expected frequency, and note that message and data rates may apply. Pre ticked boxes and consent bundled into terms acceptance are the two most common defects, and both undermine every message sent on top of them. Keep the wording shown at signup with the record, because programs change copy often.
The record is the program
For every number on your list you should be able to produce when consent was given, how, and under what wording. Keyword signups generate carrier and platform logs; web forms need the same care, storing the form version and the exact disclosure text. Numbers bought, rented, or scraped have no record behind them and should never be mailed or texted, full stop. When you migrate SMS platforms, the consent records migrate too, with the same discipline as any other consent history, because the new sender inherits the old promises.
Frequency and quiet hours are consent issues
People consent to a described program, not to unlimited messaging. A program described as a few messages a month that sends daily has drifted outside its own permission, and complaint rates will say so before regulators do. Respect local quiet hours based on the recipient time zone, cap frequency in the sending tool, and slow down when opt outs spike instead of pushing through a campaign calendar. Flash sale urgency is not an exception; it is the test of whether the caps are real.
STOP must mean stop, everywhere
Opt out by keyword has to work instantly, remove the number from every marketing segment and platform, and be confirmed with a single closing message and nothing after. The common failure is fragmentation: the number leaves the main platform but stays in a flows tool, a winback segment, or a spreadsheet someone uploads next quarter. Service messages like delivery alerts run on a separate basis and a separate list, and mixing the two is how a STOPPED number gets a promotional text that triggers a complaint with perfect evidence attached.
Related reading
These earlier guides cover connected questions in more depth: First Party Data Still Needs a Receipt: Consent for What You Collect Yourself, Consent and Cookies on Healthcare Sites and Patient Portals, and Dark Patterns in Consent Banners: What Enforcement Actually Targets.
Frequently asked questions
Can I text customers who gave their number at checkout?
For the purpose they gave it: delivery and order updates, yes, within that service scope. Marketing texts need their own opt in. The checkout is a good place to ask for it, as a separate and clearly optional step.
What frequency should we state at signup?
State a truthful range you will actually keep, like up to four messages a month. If campaigns occasionally exceed it, the stated range was wrong, and frequent exceptions mean the disclosure needs updating and the list re informed.
Do double opt ins matter for SMS?
A confirmation text that the person must answer is the strongest form of proof and filters out mistyped and third party entered numbers. Many programs use it for exactly that reason, and it dramatically reduces complaints.
What happens to consent when someone changes their number?
Numbers get recycled. A consent record belongs to the person, not the digits, which is why lists need activity hygiene: long inactive numbers should be retired rather than texted forever into strangers hands.