MailGPT, developed by Pier20.ai, integrates advanced AI models like ChatGPT and Claude into your Gmail inbox to enhance your email writing. This powerful tool assists users in transforming rough drafts into professional emails, converting meeting notes into actionable emails, enhancing message personalization with wit, simplifying complex emails, and creating custom writing styles with personalized AI instructions. The extension is free to use and only requires a Pier20 account. No additional accounts for ChatGPT, OpenAI, Claude, or Anthropic are needed.