Vistas:
Web Client / Result List / Functions:
“Send as PDF without annotations” creates zipped pdf. If multiple documents from the result list are selected and sent as PDF without annotations and one of these is a pdf, 
the resulting attached documents in the mail are pdf except the original pdf which is added as a zip file.

Download Hotfix:
https://www.docuware.com/main.asp?sig=dlx&dwdblan=neutral&dwdbname=DW6_Hot08