Email Marketing: A Beginner's Guide - Master email marketing with these 3 short ebooks from Drip.
GrowthList - A crowd-sourced list of growth hacks
HubSpot Free Email Marketing - Powerful drag and drop email marketing in the HubSpot CRM
GrowthHackers Projects - Growth collaboration software for teams 📈
Google Sheets Email Marketing - Email automation and validations directly from Google Sheets
Marketing Examples - A gallery of real world marketing case studies. Updated every day.