Filenames for attachments appear to be set to 25 characters. If you have a filename with more than 25 characters then a "~.jpg" (or whatever extension) appears at the end.
To increase this length:
To do this you can increase the variable "maxnamelength" in the macro "packName" which is within the file " macros.vm"
This appears to work fine, but this comment was added on the mailing list when I asked:
I should say that I also received this reply - which I haven't actioned!
Actually you shouldn't change macros.vm. Instead, you should override
attachmentsinline.vm and redefine this variable in there. More
specifically, copy attachmentsinline.vm from templates/ to your skin
folder, and add at the start of it:
Or, just remove the call to packName from the file, just use