You can connect @SlackHQ using @Zapier to trigger a @HubSpot Enterprise Event that uses the Transactional Email API..
You'd have to know how HTTP API's work and how SMTP API's work too, but considering these technologies are well documented you could setup @SlackHQ to respond to your HubSpot Email Marketing Campaign and Launch them too.
This would all come at a price though after the trial of more than $200/month, so do the trial first to make sure it's the solution you want. Go big or go home.
