CodeTwo Exchange Rules Pro supports installation in Exchange Server on-premises + Exchange Online / Office 365 hybrid environments. Since nothing can really be installed in the cloud, the success of the software deployment in hybrid environments relies on the proper mail flow configuration by the admin.
How does it work
CodeTwo software always intercepts emails for processing with its agent installed within the Microsoft Exchange Transport Service of the on-premises Exchange Server.
So for CodeTwo Exchange Rules Pro to be able to process emails in the hybrid environment, such environment must be set to route all emails through a server with CodeTwo software installed. Emails that do not pass through the server with CodeTwo software installed will obviously not be processed.
Inbound and outbound traffic
The best case scenario for CodeTwo software to process most of the mail traffic in the organization would be a hybrid environment configured as follows:
- Centralized Mail Transport (CMT) feature enabled in the Exchange Online / Office 365 Hybrid Configuration wizard so all outbound mail flow from Exchange Online / Office 365 is routed through the on-premises Exchange Server(s) instead of standard direct delivery to the Internet. This way you can ensure your organization's compliance policies are met (e.g. emails are scanned by your anti-spam or anti-virus Transport Agents or stamped with signatures and legal disclaimers or scanned for sensitive content by CodeTwo Exchange Rules Pro).
- MX records at the DNS host of your domain name registrar company pointed to your Exchange Server on-premises instead of routing through Exchange Online Protection (EOP). This will ensure all incoming mail flows through your on-premises server equipped with CodeTwo software.
Other scenarios are possible and may be partially supported by CodeTwo Exchange Rules Pro, however, the main point that must be kept in mind is that only emails that are routed through the on-premises Exchange Server equipped with CodeTwo software are processed.
Internally sent messages
Similarly to the external in or out traffic, internally sent messages are only processed assuming they pass through an on-premises Exchange server. Following that, three scenarios are possible:
- Either sender or recipient has its mailbox in the cloud and the other one has its mailbox in on-premises Exchange Server - emails will be processed by the CodeTwo software as they have to pass through a CodeTwo equipped server on its way to the recipient.
- Both sender and recipient have mailboxes on on-premises servers - the same as above, emails will be processed by the CodeTwo software as they have to pass through a CodeTwo equipped server on its way to the recipient.
- Both sender and recipient have mailboxes in the cloud - Unfortunately, in this scenario emails will not be processed by CodeTwo software as they do not pass through on-premises server(s) at any point of their journey to the recipient's mailbox. This is regardless of how you set up the CMT feature state or MX records because mailboxes are always searched for locally first and, if found, emails are delivered directly. Unless Microsoft provides a possibility to route such emails out of the cloud to the on-premises Exchange Server for processing before delivery, handling of such emails, not only by CodeTwo Exchange Rules Pro, but by any third-party software, is not possible.
CodeTwo Sent Items Update service configuration in hybrid setups.
Microsoft TechNet article on Centralized Mail Transport feature in hybrid deployments.
Microsoft TechNet article on Transport routing in Exchange 2013 hybrid deployments.