Commercial emailers account for 70% of spam complaints, according to [download page] Return Path’s Email Intelligence Report for Q3 2012, released November 2012. 22% of spam complaints stem from other internet service providers (ISPs), 5% from internal email, and just 3% from bots and dynamic IP addresses. Despite sparking 7 in 10 spam complaints, marketing represents just 18% of email volume, and .03% of all unique domains seen by ISPs.