This really depends what sort of file it is, but generally:Save a local copy of the file from the email, using the u2018save asu2022 command.Open the local copy in an editor. For PDF files most PDF readers have a limited ability to add text, such as using the u2018form fillu2022 commands. For other document types, you can normally just click on them and edit it. If itu2019s an image, Iu2019d suggest Paint.net as itu2019s free and you can add txt to images.One done, save the document and close it.Reply to the email, click add attachment and attach the saved document, then hit send.