Steps:
Set up a Migration Endpoint in the Source Tenant (old tenant).
Sign in to the Microsoft 365 Admin Center and navigate to Exchange Admin Center.
Set up a migration endpoint that connects to the source tenant.
Initiate the Migration:
Go to Recipients > Migration in the Exchange Admin Center.
Select Migrate to Exchange Online and choose the appropriate migration method (e.g., IMAP migration, Hybrid Exchange migration).
Complete the Migration:
After the migration completes, update the DNS records in the destination tenant to route emails to the new tenant.