You need a permanent Exchange Hybrid operation for your enterprise, but you have special network security requirements prohibiting incoming HTTPS connections from the internet to the local Exchange Server systems.

In this case, Exchange Hybrid is used to migrate mailboxes to Exchange Online securely.

You want to migrate your local Exchange organization to Exchange Online as quickly as possible.

There are two main use-cases for using Exchange Modern Hybrid. If you want to avoid a direct SMTP-connection traversing the perimeter network, you can route the mail flow through Exchange Edge Transport Server, located in the perimeter network, shown as Variant B. Variant A uses a direct two-way SMTP-connection between the local Exchange organization and Exchange Online. You can choose between two core variants. Mail flow between on-premises Exchange and Exchange Online requires an additional bidirectional connection. This connection provides inbound communication for hybrid features from Exchange Online to the local Exchange organization, e.g., moving mailboxes to Exchange Online or querying free/busy information for mailboxes hosted on-premises.Įxchange Modern Hybrid simplifies hybrid communication for the HTTPS protocol. The right arrow is the outbound connection of the two Exchange Hybrid agents installed on the Exchange servers. The left arrow is the connection used by on-premises Exchange Server for connecting to Exchange Online querying information for the local Exchange organization, e.g., free/busy information or mail-tips for mailboxes hosting in Exchange Online. The two green arrows are outgoing HTTPS connections from on-premises Exchange Server to Exchange Online. With Exchange Hybrid mode enabled, Azure AD Connect synchronizes Exchange attributes of AD objects that are relevant for hybrid operation. Note: Enabling Exchange Hybrid in Azure AD Connect does not configure a hybrid configuration in your on-premises Exchange organization. The base for a hybrid configuration is an Azure AD synchronization (grey line) with Exchange Hybrid mode enabled. The following simplified diagram illustrates the configuration of Exchange Modern Hybrid. You can read more about the differences between the two Exchange Hybrid modes in ENow's blog post, ' What are your Hybrid Options.

Exchange hybrid modern authentication