Single Opt-In
Single opt-in is legal with compliant capture, but the list inherits every typo. Validate numbers and keep strong evidence, or confirm by reply.
Single opt-in is the conversion-maximizing flow: form submitted, subscriber active. Every legitimate disclosure requirement still applies at the form — unchecked checkbox, full disclosure set, retained evidence.
Its weakness is attribution. The TCPA consent you captured belongs to whoever filled the form, but the texts go to whatever number was typed. Typos, prank entries, and recycled numbers mean some fraction of a single opt-in list never consented — and wrong-number recipients are active TCPA plaintiffs.
Mitigations short of full double opt-in: number validation APIs at capture, monitoring undeliverable and STOP rates for anomalies, and session-level consent evidence so disputes can be resolved against the actual signup.
Frequently asked questions
Related glossary terms
Double opt-in adds a confirmation step to SMS signup: after the form, the subscriber must reply YES (or click a link) before receiving messages. The TCPA does not require it, but several platforms and carriers strongly favor it.
An opt-in is a consumer's affirmative agreement to receive SMS from a brand. Marketing texts require the strictest tier — prior express written consent — captured with full disclosure and retained as evidence.
Consent proof is the evidentiary record that a recipient explicitly opted in to SMS — typically a timestamped, IP-logged, hash-locked record of what the user saw and when they consented.