
While the second option look easy, handling the new contacts, removing the obsolete contacts and updating the the user changes are tedious. Take dump of recipients and create contact with X500 address in each tenant Buy Galsync solutions for $1 per user !Ģ. Department users may still want the other department address list for proper business function.Įven if there is no requirement for other department address book, users may face mail failures due to to outlook cache of X500 (legacyDN) email address.ġ. However, when the department is moved to a Office 365 tenant, they will not see the address book of other entities since those users are synced to a different Office 365 tenant. Exchange On-premises users can easily access the address book of other co hosted departments through outlook and other email clients. This is one of the key challenges you would face in One-to-Many Hybrid scenario.

But it might be a good option for One-to-Many Hybrid scenarios until all the users are completely migrated to their respective tenants.

Centralized TransportĬentralized transport is not recommended for most One-to-One Hybrid scenarios. If you managed to convince that security guy and you do not have Federation already, simply set up password hash sync. Since you sill have that security guy, Federation is the best choice, as there is no additional complexity involved whether the hybrid is One-to-One or One-to-Many. So if you need to setup hybrid with 3 tenants you would end up in deploying 9 agents and so on. However pass through authentication recommends to have 3 agents for a tenant. Pass through authentication is probably the best suited authentication method, if you have that security guy who does not want to sync your password to Azure AD.

You might need to consider the below points slightly different, while setting up One-to-Many Hybrid than One-to-One Hybrid

Users in the on-premises Active Directory must not be synchronized to more than one tenant Hybrid modern authentication is not supported for One-to-Many scenariosĤ. At least one Exchange 2016/2019 server required in the exchange organization with latest CU to support One-to-Many Hybrid.ģ. Official Support for one Exchange to maximum 5 Office 365 tenantsĢ. Microsoft officially included the support for Single On-Premises to Multi-Tenant in the September 2020 update of Hybrid Configuration Wizard.ġ. These organizations may need to migrate each department to different Office 365 tenants. There are many organizations with On Premises Exchange hosting multiple departments each with different email domains.
