Normally, a customer who has opted out of your SMS messages can opt back in at any time by texting a keyword like START, SUBSCRIBE, or UNSTOP to your number. TxtCart records this and resumes sending to them.
There are two exceptions where texting back in will not resubscribe a customer:
The AI Agent opted them out for abuse. If a customer sent abusive, threatening, or manipulative messages and the AI Agent automatically opted them out to prevent further abuse, they cannot undo that by texting START.
You opted them out manually from the dashboard. If you removed a subscriber yourself (from Account Settings, the Subscribers tab, or a conversation), texting START back in will not automatically resubscribe them either. This is intentional: a merchant-initiated opt-out is meant to stick.
In both cases, the customer's reply is still recorded, but their opted-out status does not change, and there is currently no dashboard action that reverses it either — removing a subscriber from Account Settings or the Subscribers tab is a one-way action with no corresponding "resubscribe" or "opt back in." Every other way a customer can be opted out (replying STOP or a similar keyword, a carrier reporting the number as undeliverable, or Shopify's own sync marking them unsubscribed) still clears normally when the customer texts back in.
If a customer says "I texted START and nothing happened," check whether they were opted out by the AI Agent for abuse or by your team manually. As the product stands today, neither can be reversed; contact TxtCart support if you believe a customer was opted out in error.