We have Exchange 2013 CU13 in a Hybrid configuration with Office 365. We still have autodiscover (public & private) pointed to local Exchange.
Our in-house application needs to authenticate via SSL as Mailbox-A (on local Exchange) and Send-As any user's mailbox (in Office 365). The SMTP application points to mail.ourdomain.com, which resolves to our 2 Client Access Servers.
What are the Exchange and Office 365 requirements for getting this to work?