https://blog.cloud66.com/introducing-noticent-a-ruby-gem-for-notification-management/

With Noticent, you can:

• Define different “channels”, like email, Slack, Webhooks, mobile push,…
• Specify the alerts for different parts of your application and how they should be delivered to the users.
• Use simple methods to subscribe and unsubscribe users to each one of the alerts on different channels.