Before starting the configuration of an initially set SEPPmail Secure E-Mail Gateway instance, the basic configuration steps are to be observed at all times (see Commissioning The Secure E-Mail Gateway Appliance, especially Information Required For Commissioning and Setting Up The Firewall/Router.
After the above-mentioned steps have been completed, the SEPPmail Secure E-Mail Gateway can be prepared for the secure communication with M365EO.
For an installation in Azure, the SEPPmail Secure E-Mail Gateway is available in the Azure Marketplace. A script for the automatic creation of a Cluster can be found in the further information provided under https://www.seppmail.de/produkte/seppmail365/, if necessary (see link to the "GitHub Repository").