Hybrid Setup Recommendations

If you plan to use eperi sEcure Platform in an Exchange Hybrid Environment, several aspects should be considered.

Requirements

  • Centralized mail transport has to be set up in order to route outbound mail to external recipients from your Exchange Online organization through your on-premises servers for decryption.
    • To achieve this the option Enable Centralized Mail Transport should be configured in the Hybrid Configuration Wizard.
  • Exchange (Online) Send Connectors have to be adjusted to route mail between on-premises and remote recipients through your Postfix server, ensuring that emails are encrypted or decrypted between organizations, depending on the destination.
  • The Exchange Online Receive Connector has to be configured to be able to receive mail from the sending on-premises mail relay (e.g. Postfix or 3rd party mail relay).
  • The autodiscover CNAME record has to be configured to point to your on-premises Exchange server which will automatically redirect users to the Exchange Online autodiscover service if they have a remote mailbox.

Postfix configuration

The actual mail flow configuration depends on the individual setup of your hybrid environment.

The following is an example of what the Postfix transport map /etc/postfix/transport might look like in a hybrid environment. It is important that both the on-premises and cloud mail domains are included in the configuration.
demo.eperi-cdp.com smtp:[exchange.local.dom]:25
<tenantName>.mail.onmicrosoft.com smtp:[<tenantName>.mail.protection.outlook.com]:25
<tenantName>.onmicrosoft.com smtp:[<tenantName>.mail.protection.outlook.com]:25
* smtp:[exchange.local.dom]:25