What is Double Opt-In (SMS)?

Double Opt-In (also called confirmed opt-in) is a two-step SMS consent process. In the first step, the customer provides their phone number through a form, keyword, or other method. In the second step, they receive a verification text asking them to confirm by replying "YES" or "CONFIRM." Only after this confirmation are they added to the active subscriber list.

This contrasts with single opt-in, where the customer provides their number and is immediately subscribed without a confirmation step. While single opt-in is legally sufficient under TCPA, double opt-in provides stronger proof of consent and results in a higher-quality subscriber list.

Double opt-in is particularly recommended for industries with higher compliance requirements — alcohol, tobacco, supplements with health claims, and any category where consent disputes could be costly.

The process flows in two steps. Step one: the customer enters their phone number via a web form, keyword text, QR code, or checkout. The system sends an immediate verification text: "Reply YES to confirm your subscription to [Brand Name]. Msg & data rates may apply. Reply STOP to opt out."

Step two: the customer replies YES (or the specified confirmation word). Only then are they marked as a confirmed subscriber and begin receiving marketing messages. If they don't reply, they remain unconfirmed and receive no further messages.

Some platforms implement a time window for confirmation — if the customer doesn't confirm within 24–48 hours, the pending subscription expires. This prevents stale opt-in attempts from cluttering your list.

Double opt-in produces a cleaner, more engaged subscriber list. Every subscriber has actively confirmed twice that they want your messages. This means higher engagement rates, lower opt-out rates, and fewer spam complaints — all of which improve deliverability.

From a legal standpoint, double opt-in provides stronger evidence of consent. If a subscriber disputes that they opted in, you have a record of both their initial signup and their confirmation reply. This is valuable protection against TCPA claims.

The trade-off is lower list growth. Some percentage of people who provide their number won't complete the confirmation step. Typical confirmation rates range from 50–80%. The subscribers you lose in this step are the least engaged — the ones most likely to opt out or ignore your messages anyway.