Mailbutler's Smart Assistant is an AI-powered email management tool designed for Apple Mail, Gmail, and Outlook. It streamlines email communication by offering features such as Smart Compose for drafting emails, Smart Respond for generating replies, and Smart Summarize for quick overviews of email content. Users can customize the tone and style of their messages, improve grammar and spelling, and easily find tasks and contacts from their emails. With a user-friendly interface, the Smart Assistant enhances productivity and efficiency in managing email correspondence.