Topic Last Modified: 2012-09-18
On the Certificate page, select a certificate for the hybrid deployment configuration. This certificate will be used to authenticate secure mail transport between your on-premises Microsoft Exchange and Exchange Online organizations.
The certificate you choose must be one purchased from a trusted third-party certificate authority (CA) and installed on your Exchange 2013 or Exchange 2010 Edge Transport servers. Self-signed or any certificates generated by your organization as the CA aren’t supported in hybrid mail transport.
For more information
Certificate Requirements for Hybrid Deployments