An RSS (Really Simple Syndication) feed is a format used to publish regularly updated content, such as blog posts or news articles. It can be used to subscribe to a website's content so that you receive updates automatically.
To use an RSS feed in a transactional email, you can set up an automated process in Flowmailer that pulls in the latest content from the feed and includes it in your email - using the External Data step. This way, your recipients will receive the latest content every time they receive an email from you without you having to create and send each email manually.