User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

Please integrate the feature of post-it/sticky notes to Thunderbird core. These are persistent sticky notes associated to mails. This feature substantially increases productivity when working with emails.

Currently, this feature is provided by the excellent add-on XNote++, which is one of the most useful extensions, but which will not be ported to Thunderbird 78+. Since sticky notes are a real productivity booster and a competitive advantage (e.g. over MS Outlook), I would like to ask you to integrate it into Thunderbird core.

• It is a brilliant idea to have persistent yellow post-its/sticky notes attached to individual emails. It allows for dozens of productive uses such as info on conversation follow-ups, info whether invoices were paid, and many more.
• The current implementation:
  ** feels like an integral part of Thunderbird
  ** is nicely integrated with the tagging feature of Thunderbird by adding the XNote tag
  ** works flawlessly for many years and it is ranked 5/5 stars
  ** provides a feature which does not exist in competing email clients (e.g. MS Outlook)
  ** XNote++ it is a featured extension.
• An integration into core Thunderbird would also allow for searching notes (which Xnote currently does not provide) and would avoid dataloss from users of the current add-on.

https://addons.thunderbird.net/en-US/thunderbird/addon/xnotepp/
https://www.froihofer.net/en/xnote.html

Similar to bug 12306