Option to outsource message templates to notification service provider
Description
Unity allows for plugging notification channel implementations but all notification channels are responsible only for delivering a prepared message. It was requested to provide a feature to integrate with notification providers (like MailChimp's Mandrill or HubSpot) which also embed message templating functionality. In other words in case of such integrations Unity core should pass template id and variables to the notification channel implementation.
Unity allows for plugging notification channel implementations but all notification channels are responsible only for delivering a prepared message. It was requested to provide a feature to integrate with notification providers (like MailChimp's Mandrill or HubSpot) which also embed message templating functionality. In other words in case of such integrations Unity core should pass template id and variables to the notification channel implementation.