I print to a pdf printer driver wich add a stamp and save it - but with at "Mail Attachment server" + saved filename.
Add parameter to the Print file properties what take care of "Mail Attachmment server" + filename - to be able to print to the physical printer
Delete file - add parameter who take care of the "Mail attachment server" - other wise the appz cannot delete the file.
The best of the above Wass to keep the orginal saved filename all way against the appz.
I use Universal document converter 6.8 to add stamp - trye to test yourself.
We ar not able to select under service the user account exp administrator - without you cant write to network shares