how do I add a note to an email using outlook

BTW- you have to select the "simplified" ribbon instead of the "classic" ribbon to get the ellipsis (3 dots) to show up in the upper right (possibly next to the Zoom) to see the Actions feature. This works like a charm though. Thank you.

This seems to work in "Microsoft 365 Apps for enterprise" v.2408.

It changes the title in the message, but does not change the title (for me) in the message list, so there is no indication a note has been added unless you're viewing the message directly. If you Forward/Reply then the note _is_ included in the subject and in the included "Subject:..." line; so if the note is not to be shared you'll have to be really careful!

THIS FEATURE DOESN'T EXIST AND IT'S BEEN AT LEAST ONE YEAR SINCE USERS WERE TOLD IT WILL BE REINSTATED

I cannot find the notes button in the email

On your toolbar, look for the group "Move" the icon in that group that looks like a document and open envelope. Click on the arrow next to it and it will give you the option of Edit message.