# What if a reader's email changes on our side?

_Category: Domain, access and SEO_

Send an `external_id` claim in every token, from the first sign-in, and the reader keeps the same account in your help center when their email changes.

HelpCenter.io recognizes an SSO reader by their email address or by their `external_id`. Use your own stable user ID, the one that never changes, as the `external_id`. When a token arrives with a new email but a known `external_id`, HelpCenter.io signs in the reader it already knows.

```
{
  "jti": "the key HelpCenter.io sent",
  "iat": 1767225600,
  "exp": 1767225900,
  "email": "new.address@example.com",
  "name": "Jane Doe",
  "external_id": "4815"
}
```

- **Add it from the start.** A reader created without an `external_id` stays matched by email only, even if later tokens include one. A changed email then creates a new reader.
- **Details stay as they were.** HelpCenter.io keeps the email, name and other details a reader was created with, so their comments keep showing the name from their first sign-in.

See [JWT claims and validation rules](https://developers.helpcenter.io/content/jwt-claims) on the developer portal.

## Related articles

- [Sign readers in with your own login (JWT SSO)](https://self.helpcenter.io/content/jwt-sso)