The best practices for Office 365 domain migration include careful planning, data backup, and thorough testing before making any changes. Organizations should first identify all users, mailboxes, groups, and services connected to the domain and migrate the required data to the destination tenant. Lowering DNS TTL values in advance can help reduce propagation delays during the switch. Many businesses use the SysInfo Office 365 Tenant to Tenant Migration Tool to migrate mailboxes, OneDrive, and SharePoint data securely before transferring the domain. After the migration, administrators should verify mail flow, user sign-ins, and access to Microsoft 365 services to ensure everything is functioning properly.
Read more: https://www.sysinfotools.com/blog/move-domain-between-office-365-tenants/