To retrieve subscriber related information about subscription history, his source and mailing list relation, you have to open the subscriber’s profile. Go to Subscriber - Management --> Edit Subscriber and search for a subscriber, in this example "bcadmin@domain.de". Afterwards you are able to retrieve all data required about this subscriber.
The first table below the email address shows this subscriber's list relation. Time of subscription/unsubscription is displayed next to the corresponding mailing list.
Fig. 7.3.5.1 - Subscriber's history
You as a sender have to be able to provide data about time and source of subscription as well as IP-address at that time. BACKCLICK supports you in doing so. Clicking the 
-button next to a mailing list displays the entire subscription and unsubscription history of this subscriber, including the so-called "referer" and IP-address. Even if a subscriber subscribes and unsubscribes multiple times, BACKCLICK will save all data.
Fig. 7.3.5.1.1 - Subscriber - Statistics
Clicking the IP address allows you to identify the registered owner using the "RIPE Whois Database". If the subscriber subscribed to your newsletter using a form on the internet, this website will show as source. Clicking the "Referer" ("Administrationsoberfläche" in this case) takes you to the "RIPE Whois Database"
Subscriber’s database fields
Below these statistics you will find all subscriber's database fields together with corresponding content. You may modify these and confirm your changes by clicking the "save"-button.
Fig. 7.3.5.2 - Subscriber's history
Click the "back"-button in order to return to Subscriber - Management.