Assegnate 4 su 5 stelle

Agreeing with blubb. It's very useful. But we extremely need the tree of subfolders and option to archive by size (for example, 3.9 GB).I propose the following scheme:We have folder Work in Inbox (for example). When the file Work gets critical size, the subfolder Work{YYYYMMDD_HHNNSS} (needs the specific mask) will be created and all files from Work will be moved to this subfolder. Files with specific mask {YYYYMMDD_HHNNSS} do not need to archive.

Sorry, but I will not implement this feature in my addon, because I think that it will be difficult to implement it using Thunderbird Javascript API. Additionaly, moving 3,9 Gb of data using Thunderbird Javascript API will be extremely slow. Instead, you can use some script at start of Thunderbird, for example here is my simple bash script that can be used on Linux to move Inbox folder into archive folder:
countzero@countzero:/media/samba/Alex|⇒ cat start-thunderbird.sh
#!/bin/bash
NOW=`date +%d.%m.%Y`
find ~/.thunderbird/*/Mail/*/Inbox -type f -size +1G -exec mv '{}' '{}'_$NOW \; -exec mv '{}'.msf '{}'_$NOW.msf \;
/usr/bin/thunderbird
One small problem with this solution: on some systems sometimes Thunderbird does not rename correctly Inbox folder into archive folder (may be because it is still contains Inbox flag or some other reason), and you will have two folders named Inbox in Thunderbird. And this solution is platform-dependent.