Blacklist is a list of suspended/excluded publishers (ad networks) or sources from a marketing campaign that have fraud signals because of unmet targeting conditions or low quality traffic. 

Blacklisting is very important for mobile advertisers because fraud has become a much more serious issue than ever before because of increasing sophisticated ways of fraud. Fraudsters can easily change Device IDs and IP addresses and it makes it hard for app advertisers to find the most effective marketing channels and sources.

 Mobile advertisers prefer real time blacklisting to avoid low quality and fraudulent sources while marketing campaigns are running. It is a campaign optimization process that every mobile advertiser should be aware of.