I’m not sure you can do that using SNDDST without using the QDLS file system. You can write your own command using the APIs. Or you might want to try this first:
Go to http://www.help400.de/Eng/Freeware.htm and download the SNDM (Send Mail) command. It will send attachements from the IFS Root style directories.
Just a suggestion (you may already know this)… You should consider creating a folder or folders under the root and move things there. You shouldn’t be sharing the root because you’ll be opening the whole system up including the QSYS.LIB system. I use the /home folder and then create folders from there based on user_profile. But you can create your own.