This guide elaborates why you in some cases have to explain and prove how a recipient subscribed to your newsletter.
When a subscriber is using Hotmail, Yahoo!Mail or TDC Webmail, and marks your newsletter as "Junk", Ubivox receives a notification stating that a subscriber has "complained" about receiving the newsletter. The subscriber is then, automatically, suspended from the list. This guide elaborates complaints and how they are handled in Ubivox.
How does the function Subscriber stoplist work, and how do you add a subscriber to the list.