WE PUSHED ACQUISITION TOO HARD. COMPLAINTS FOLLOWED

Summary from the TLDR Marketing newsletter

After increasing co-registration subscribers for its Trivia Nut newsletter, a publisher saw Gmail's spam complaint rate exceed 0.30% for 4 days and peak at 0.49%. It cut incoming subscriber volume by 50%, bringing the next reported rate down to 0.06%. The publisher recommends monitoring Gmail's spam rate separately through Postmaster Tools and checking acquisition sources when complaints rise.