I really like superReply. It's great to see suggestions on how your sentence can improve on tone and structure. I do disagree with some suggestions though, and it isn't always accommodating to my writing style. I have found a few mistakes in terms of its suggestions as well.
AI Email Response Generator - superReply is an AI-powered email response tool that suggests ready-made responses tailored to specific emails, helping users save time, avoid writer's block, improve grammar, and sound professional
It uses smart technology to generate personalized replies based on email conversations and user history