A new subscriber signs up for a newsletter at Cloud Kicks and receives a welcome...

When a new subscriber signs up for a newsletter and receives a welcome email, they are automatically marked as "Active" on the All Subscribers list in Email Studio. This status indicates that the subscriber has been added to the list and is eligible to receive emails. The "Active" status is assigned by default unless the subscriber opts out or is otherwise suppressed.

Active Status Explanation: Active subscribers are eligible to receive emails unless they unsubscribe or bounce, at which point their status may change.

Salesforce Documentation Reference: See Subscriber Status Definitions for more on subscriber statuses in Salesforce Marketing Cloud.