If you are running Exchange 2013 CU8 or earlier and running in Hybrid configuration with Office 365, this will impact you.

Exchange 2013 CU9 or later are not impacted.

On April 15 2016, the certificate used to secure the communication between your on premises and Exchange Online (Office 365 TLS certificate) will be renew.

After this date, if you don’t take action, your hybrid mail flow will be impacted and it will stop working.

Actions

OR

  • On each Exchange servers used in the hybrid mail flow, run the following commands with Exchange Management Shell
    • $rc=Get-ReceiveConnector |where {$_.TlsDomainCapabilities -like "*<I>*"}
    • Set-ReceiveConnector -Identity $rc.Identity -TlsDomainCapabilities "mail.protection.outlook.com:AcceptCloudServicesMail