Rated 5 out of 5 stars

This was very useful, especially with send later, to delay an email to self as an attachment to easily be able to reply all.
sadly, not compatible with newer versions of Thunderbird

Hi,
I'm glad you like my add-on. The reason why it isn't updated anymore, is because most of the functionality has been incorporated in Thunderbird core, ever since version Thunderbird 24. See also bug 508250.
Kind regards,
Onno Ekker
https://bugzil.la/508250