You cannot set the filename of a file you attach to an arbitrary one. This means if you are attaching from a URL say with some parameters, you get a pretty nasty filename. I have made the necessary changes for this, along with fixing bug 34786, and introducing a further set of features which allows for having text and html multi part emails (will be in the next report, along with patches for all three)
Resolving. Taglib has been retired.