I found a work around for this myself. For anyone who might be interested:
During a process in a Workflow (in my case, when I receive an email with an attachment), I create these files in a folder in my File System, as well in my SharePoint library. Then I have a PowerShell Script that runs daily, which prints out all these files to my default printer and deletes it afterwards.
Here the script:
dir "C:\Test\ *.pdf" | ForEach-Object {Start-Process -FilePath $.FullName -Verb Print -PassThru | %{sleep 10;$} | kill}
Get-ChildItem -Path C:\Test -Include . -File -Recurse | foreach { $_.Delete()}
This way, it still works like I wanted to.