Just to clarify a little.
There's --mbox, for mbox formatted files, --mbx for mbx formatted files, --file for a single message, and --dir for a directory of files with 1 message per file.
The code will assume --file or --dir as appropriate in most places.
Ahh, nice catch Theo... I hadn't noticed the new --mbx feature of sa-learn...
However, are Mozilla .mbx files are in mbox or mbx format ? I know in 1.0 they were mbox, but have they since changed to mbx, or did they just shorten the filename?
(The reason I bring Mozilla into this is the OP uses Mozilla for Windows)