Set up Visual Studio 2017 for Azure

Azure Developer Tools

https://azure.microsoft.com/en-gb/tools/

Azure Quickstart Templates

https://github.com/Azure/azure-quickstart-templates

Deploy and manage Azure resources

https://github.com/Microsoft/HealthClinic.biz/wiki/Deploy-and-manage-Azure-resources

OPNSense SMTP NAT Port Forward

One of the options to allow SMTP trafic to internal email server is to to set NAT Port Forward

RequireTLS

Set RequireTLS on Exchange Server default receive connector (port 25)

Test SMTP connection using https://testconnectivity.microsoft.com