Forum Discussion

Naxiu's avatar
Naxiu
Copper Contributor
Mar 31, 2026

Preserving permissions during EXO migration

Hi,

Can you help me understand the outcome of preserving the permissions in our scenario.

Exchange Server 2016 (soon Exchange SE) in a hybrid with Exchange Online.
We are moving 75% of the mailboxes to Exchange Online.

What ways will preserve or break the full-access or sendas permissions?

I guess best way would be to migrate both the user and the shared mailbox at the same time in the same batch to keep the permission?

 

If we migrate the user in batch 1 and shared mailbox in batch 2 will that preserve/break the full access/send as?

If we migrate the shared mailbox in batch 1 and usermailbox in batch 2 will that preserve/break the full access/send as?

If the permission is linked directly on the shared mailbox or via a security group is there a difference?

Thanks!

2016
exchange online
hybrid

1 Reply

  • Lucaraheller's avatar
    Lucaraheller
    MCT
    Apr 20, 2026

    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.