It'd be more clever to store the notes as replies to your own address, connected to the email; and have the extension see them and render them differently (the

It'd be more clever to store the notes as replies to your own address, connected to the email; and have the extension see them and render them differently (the extension can store the notes mails with a particular keyword/GMail label). Alternatively they can be draft replies, so you can edit the notes, but that might pollute your Drafts folder. An advantage of the "reply-to-self" is that the notes would be stored in GMail itself and are viewable on all your devices, including ones without this hypothetical extension. I guess the extension can also emulate an editing feature by deleting the old version of the "note" email and creating a new one..