last time i've opened a call regarding this, they said is not supported (you must do manually).
if you want to do you must costumize the package lifecycle
then make a costum call (java) to external ftp (java ftp possibly) and pass parameters to ftp (including username and password, other costumization in java faor generation and sending the password to the recipient of the package)
after you can take back logs from ftp and update package lifecycle attaching the success connection and the download of the package.
there is a lot of work for costumization and integration
can also look into Windchill ERP Connector module that is a good base to process automation (requires license and i suppose is not very affordable)
there is also projectlink (collaboration function)
I am also interested in this configuration. I see that your post is several years old, did you solve this problem? One thought I had was to create a robot in the deliver workflow that would accomplish this.