The current version is 52.1.1 Version 53 may be a beta version. All addons are the responsibility of the addon author. You might find info on the addon webpage from another user of that addon extension. You could also try contacting the author. https://addons.mozilla.org/en-GB/thunderbird/addon/awesome-auto-archive/ at the bottom, it says 'Developers Comments'. the info under that option offers a link where to report issues. Located this: https://github.com/wangvisual/autoarchive/issues