EasyEmail - Gmail plug-in that helps you write emails quickly
Grammarly - Clear, effective, mistake-free writing everywhere you type.
Text Case - Format any raw text on iOS and more 📝
ProWritingAid - For the smarter writer. A grammar checker, style editor, and writing mentor in one package.
Really Good Emails - A large collection of good product email design.
Gramara - AI grammar correction with transformers