Preserving permissions during EXO migration

Hi,

Best practice is to migrate the user mailbox and shared mailbox in the same batch whenever possible.

If they are migrated in different batches, permissions such as Full Access may continue working, but Send As is more likely to have delays or require revalidation during coexistence.

Using security groups can work well, but adds sync timing and membership variables. Direct permissions are usually easier during migration.

My recommendation:

• Migrate dependent users + shared mailboxes together
• Export permissions before migration
• Validate Full Access / Send As after each batch

This gives the cleanest experience in hybrid environments.

Hope this helps.