I've been trying to solve this one myself. I have managed to get the following to work to attach multiple files. I ended up making some small changes to one from kde-apps.org. Place a shell script called attach_mail_service, make sure it's executable, in your home directory bin ie: ~/bin. The contents are as follows:
# Script created by ASID
# Attach files to thunderbird
#subject="mailing files: "
for i in $*
count=$(( $count + 1 ))
if [ $count -eq $# ]
if mozilla-thunderbird -remote "ping()" 2> /dev/null ;
mozilla-thunderbird -remote "xfeDoCommand(composeMessage,attachment='$temp')"
mozilla-thunderbird --compose "attachment='$temp'"
Now place a file named AttachToThunderbirdMail.desktop in your ~/.kde4/share/kde4/services/servicemenus directory. The contents are as follows:
[Desktop Action attachToEmail]
Name=Attach to Email
You should be able to right click on a file or multiple files and have a context menus of Action | Attach To Email. It works for me. YMMV.