When faced with this challenge, it became apparently that there wasn’t a great deal of information available around how to smoothly remove an hybrid configuration from an Exchange organisation, whilst MS walk through the process in the following technet blog entry the order in which MS suggest performing the steps required wasn’t actually possible and resulted in a number of errors. I therefore wanted to provide some clarity around the process/ordering. This process covers hybrid configurations in both Exchange 2010 and Exchange 2013.
Firstly I assume the following activities have already been completed;
- All required mailboxes have been migrated off of the on-premise environment across to Office 365
- If necessary all public folder content has been migrated across to Office 365, either to shared mailboxes or traditional public folders.
- All Exchange related DNS entries (autodiscover,OWA etc) have been re-pointed to O365
- All MX records for SMTP domains that are being managed by O365 have been re-pointed to O365
Once these activities have been completed we can start on the steps required to remove the hybrid config;
- Remove the organizational relationship from the on-premise environment as follows; ‘Remove-OrganizationalRelationship -identity “name_of_org_relationship”. The identity of the organizational relationship can be obtained by using the ‘Get-OrganizationalRelationship’ if required.
- Remove the organizational relationship from the O365 tenant as follows; ‘Remove-OrganizationalRelationship -identity “name of_org_relationship”, Again the identity of the organizational relationship can be obtained by using the ‘Get-OrganizationalRelationship’ if required.
- Remove the federated domain(s) from the on-premise environment as follows; ‘Remove-FederatedDomain -domainname name_of_domain
- Remove the Email Address Policy/Policies associated with those SMTP domains that have been moved to O365. This can simply be performed from on the on-premise Exchange admin console
- Remove the Accepted Domain entries from the on-premise Exchange admin console for those SMTP domains that have been moved to O365. Again this can simply be performed from on the on-premise Exchange admin console.
- Remove the federation trust from the on-premise Exchange environment as follows; ‘Remove-FederationTrust -Identity “Microsoft Federation Gateway” By default the hybrid configuration wizard in Exchange 2010/2013 names the federation trust “Microsoft Federation Gateway”.
- Remove the remote domain associated with the Exchange hybrid configuration using the on-premise Exchange Admin Console. This will be named something like “Hybrid Domain – tenant_name.mail.onmicrosoft.com”
- Remove the SMTP send connector from the on-premise environment as follows; ‘Remove-SendConnector “Connector_Name”‘
- Remove the inbound and outbound SMTP connectors that were created by the hybrid configuration wizard in the Exchange Online Protection Administration Console
- Finally remove the HybridConfiguration object from within Active Directory. This isn’t supported in Exchange 2010 and its perfectly fine to leave the object in AD without any adverse effects. If however Exchange 2013 is being used in the hybrid configuration, the following PS command can be used to remove the HybridConfiguration object; Remove-HybridConfiguration
Once those steps are complete, all references to the previous hybrid configuration are removed leaving two separate and distinct Exchange environments, CompanyA on-premise and CompanyB in O365.