Message templateThe default is <subject> : <body>, which are configured with messageSubjectTemplate and messageBodyTemplate below. See
Messaging Services Templates for details on the template language.
Optionally, you can configure a proxy or the error reporting channel name.
When entering configuration values in the UI, use unescaped characters, such as \t for the tab character. When entering configuration values in the API, use escaped characters, such as \\t for the tab character.