Nawvel - Nawvel is a handy-dandy library of tried, tested & curated resources.
Really Good Emails - A large collection of good product email design.
Micro-SaaS - All you need to build your own SaaS at one place.
Good Email Copy - Email copy from great companies.
Makerbook - A directory of the best free resources for creatives
Good Sales Emails - Best sales emails from great companies