A dotted line from a "Group By" component to a "Filter" component means that a property from the "Group By" is referenced by the "Filter" component. For example, if you group customers by age and then filter them by average spending, you need to reference a property from the "Group By" component, such as .pxSegment, in the "Filter" component. A dotted line does not indicate a one-to-one relationship, an evaluation order, or a copying of information between components

To implement this requirement, you need to create an external email treatment and use an external tool to design the email. An external email treatment is a type of treatment that allows you to use a third-party email service provider to send emails to your customers. You can configure the external email treatment with the name of the provider, the authentication details, and the template ID that corresponds to the email content that you design using an external tool. This way, you can leverage your existing tools and processes for sending emails, while still using Customer Decision Hub to select the best actions and treatments for your customers. Verified Reference: Pega Academy - Decisioning Consultant - Creating external treatments