Developer does not support his add-on for Thunderbird since 2015.
I’ve managed to modify it (using Experiments API) to work in TB 78.
A have already posted it in Issues comments on add-on’s github page.
I think the original author would have to add you as co-author or something like that.
Maybe @caitlin could write here more details? Thanks!
It would be a huge security risk if anyone could release update for any addon.
In ideal scenario you would simply create pull request in his github repository with a correctly set "strict_min_version": "78.0" (so that users of old 68 are not upgraded) and he would then merge and release.
But if he abandoned the project, then you would just have to release new addon under new name.
@AleksUkr73
It much better if you get the author’s blessing if you can. At best you can own the ATN listing. Or they will put a comment on the original listing and in github pointing to yours.
And if you publish are you prepared to maintain it? If it contains an experiment it may require more work with every release.
I’m not mastered in Java or programming itself and not going to make fork or maintain it.
So I left link to Github page with my solution on add-on’s page in review comment.
Hope it will help add-on users.
Thunderbird has now the extension finder linked directly from within Thunderbird on incompatible add-ons, to guide users to alternatives/forks. So if you do decide to fork it and upload it to ATN, we can make it discoverable.