Delegate access can be used to access your users data and should be setup or used when application impersonation cannot be used.
Where possible, you should use application impersonation. If you are migrating to or from BPOS, Office 365 Kiosk or Office 365 for small business, then you need to use delegated access. For migrations from BPOS (Microsoft Online Services), you should just be able to specify the email address of an admin user in the tool settings, and specify ‘Delegated Access’ as the ‘Credential Method’ and do not need to set anything else up.
Login to the Office 365 Exchange Admin Portal.
Go to 'Recipients' then under Mailboxes double-click the user you wish to delegate access to. Go to 'Mailbox Delegation' and click the '+' symbol under 'Full Access'
Select your admin user then click 'add →', then OK.
Click 'Save' in the 'Edit User Mailbox' window. Your admin user now has the required access.
Repeat for each user you wish to migrate.
To setup delegated access do the following:
- You should choose or create a user that will be given delegated access to all mailboxes.
- Start a PowerShell session. If you are migrating to Office 365, or are not running PowerShell on an Exchange server you will need to setup a remote PowerShell session.
Run the following command in the PowerShell session, replacing ADMIN with the user that will perform the migration: