Rated 5 out of 5 stars

It is so useful to be able to add any info you like to received emails, I've wanted this function for so long. Good work, Thank you.

One small glitch, version is not found when checking for updates to v 1.1 or show on the main page until you view the version info at the bottom of the page. The xpi file is named slightly differently, so this maybe why.

This review is for a previous version of the add-on (1.1). 

Every version should be reviewed by the mozilla developers before it becames actual on the site. The review is needed to cut off insecure or of a poor quality add-ons. It took a couple of months for the first one. All versions are available on https://addons.mozilla.org/en-US/thunderbird/addon/messagenotesplus/versions/.
Thanks for the feedback.