Best of the inbox: the sender-split that cut spam complaints 71%

Best of the inbox: the sender-split that cut spam complaints 71%
This week's case studies all share one trait — the operator measured a single variable and reported the number. No vibes.

📥 Swipe
— The promo/transactional domain split — A list owner moved receipts and password resets to mail.brand.com and offers to go.brand.com. Spam complaints on the money domain dropped 71% in six weeks because one bad blast could no longer poison receipts. Worth your time: it's the cleanest argument for subdomain segmentation I've seen written up.
— Why complaints were the real KPI — They tracked Gmail Postmaster spam rate, not opens. The split pulled it from 0.31% to 0.09% (Google's danger line is 0.30%).

Made the cut because it isolates one move and one metric. No bundle of ten changes you can't untangle.

Saved you ~2 hours of reading deliverability threads that never show the number.