MailCompose Assist powered by GPT-3.5 is a Chrome add-on developed by a4-craft that aims to automate the process of composing emails in Gmail and Outlook. With this tool, users can save time by eliminating the need to worry about honorific expressions and cultural variations in email writing.

The add-on offers two main functions. Firstly, users can create a new email by clicking the "Create New Email" button and filling in the desired content in the bottom left corner. Once the button is clicked, the add-on takes about 10 seconds to generate a new email with automatically inserted sentences.

Secondly, users can create reply emails by simply dragging and dropping the text they want to reply to and clicking the "Reply" button. Similar to the new email creation function, the add-on takes about 10 seconds to generate the reply message.

Detailed instructions on how to use MailCompose Assist powered by GPT-3.5 can be found in the provided link.

Overall, this add-on offers a convenient solution for automating email creation, saving users time and effort in composing emails in Gmail and Outlook.