Rated 5 out of 5 stars

Please update to 78

Thanks for your feedback.

But it is not possible to update MRC Compose to TB78 for 2 reasons :
- since TB70, there is a new UI for recipients that replace MRC Compose. By some ways it is better : recipients are not simple text, but 'bubbles'

- since TB70, some underlying technology (XUL) has been removed and MRC Compose uses XUL that. So now MRC Compose cannot be ported to new Thunderbird.