Run a manual synchronization to bring up addresses with the new domain name, without deleting the old one:

Appoint a global administrator for the Letsignit platform with the new domain name (mandatory).

This article shows you how to do it: How to change your collaborator's role ?

Uncheck the old domain name in the synchronization edition and restart a manual synchronization.

This article shows you how to do it: How to filter domain names when synchronizing my directory?

Email addresses with the new domain name are now uploaded to your platform.

Manually add a user with the new domain name to the Letsignit platform and name him global platform administrator (mandatory).

This article shows you how: How to change your collaborator's role ?

Remove users with the old domain name from the platform, taking care not to remove the new administrator you've just added.

This article explains how to proceed: Team: Team : How to remove massively some users ?

Import your users via the CSV file by following this article (part 2): Users : How to import them on your platform?

Our customer support team is at your disposal if you have any questions ;)