Well, seeing two versions and comments of Steve Brewin...
Two versions compared + (positive) vs - (negative)
+ 70 lines of source code for Mailet / Matcher
+ Scripts in separated files
+ Don't need restart James for reload changes of scripts
- Don't have mutli languaje scripting
+ BeanShell is true Java (JSR-274)
+ KISS principle,... Keep It Simple, Sweetheart!
ScriptedBSF (IBM Bean Scripting Framework)
- 500 lines of source code for Mailet / Matcher
- Scripts inline (SAR-INF/config.xml)
- Need restart James for reload chanages of config.xml
+ Mutli languaje scripting
+ BML, JScript (only win), Mozilla Rhino, NetRexx, PerlScript, VBScript, Jacl, JPython, LotusXSL
? Complex / Featured
this is in broad strokes, normally would decide me by the simple thing (KISS principle), although I suppose that the support for several languages also would be useful.
Before the doubt, I would put both! : -)