Our organization is planning to move its Microsoft 365 environment to another tenant, and we are trying to identify the best approach for migrating shared mailboxes and calendar information. Most discussions about Office 365 tenant to tenant migration focus on individual user mailboxes, but our organization also depends on shared mailboxes used by sales, support, finance, and administrative teams. These accounts contain important customer conversations, departmental correspondence, and historical records that must remain accessible after the migration.

One challenge is understanding how shared mailbox data should be transferred when the destination tenant has a different user structure. We need to ensure that the original mailbox folders, email attachments, and message details are preserved. At the same time, the employees who previously had access to these shared mailboxes should receive the appropriate permissions in the new environment.

Calendars introduce another consideration. Some shared mailboxes contain schedules, appointments, and meeting-related information that different departments use for daily coordination. I would like to know whether these calendar items can be migrated along with mailbox content or whether they require separate preparation and configuration. We also need to consider resource mailboxes and their associated access settings.

While researching Microsoft 365 tenant migration solutions, I came across the SysInfo Microsoft 365 Tenant to Tenant Migration Tool, which provides mailbox migration capabilities and options for handling multiple Microsoft 365 workloads.

For administrators who have completed a shared mailbox migration, what approach worked best? Did you recreate mailbox permissions manually after transferring the data, or did you use a mapping-based process? I would also appreciate suggestions for checking calendar entries, shared mailbox folders, and delegated access before removing the old tenant environment.
https://www.sysinfotools.com/o365-tenant-to-tenant-migration.php