Have you tried mailmindr? There's also ReminderFox, which states it's compatible with 60.4, so it might work with 60.9.1.

just tryed mail minder it does not work either, they both just attach themselves to a new msg as if i was going to send them to someone.]

thanks

How did you install the add-ons?

https://support.mozilla.org/en-US/kb/installing-addon-thunderbird

just left clicked them in download folder, also clicked open. cant figure idf i have old or new version of tb

Open Tools/Add-ons/Extensions in TB, click the gear icon next to Search, Install add-on from file..., select the xpi file you downloaded.

Your TB 60.9.1 is the latest version in the 60 branch, and it will eventually be updated to 68 if you have auto update enabled in Tools/Options/Advanced/Update. Change the setting to 'Check for updates...' if you think you might want to stay on 60.

got the mail mindre working , but cant find the alarm that it mentions thanks for the installation intructions

I don't have a TB 60 setup to try mailmindr, but you can contact the author from the address on the add-on site. Check the Actions in the Resubmission window to see if there is an alarm.

sorry i dont understand this "Check the Actions in the Resubmission window to see if there is an alarm."

See the first picture on the mailmindr page.