To enable the advanced protocol function, please do the following.
Copy the file linked below on the affected system (in the context of the user where the problem occurs) under "C:\Program Files (x86)\gotomaxx\pdfmailer6\pdfmailer".
https://download.gotomaxx.com/maxxPDFMAILER/PDFMAILER7/log.ini
Now create the directory "C:\Temp\".
Reproduce the error.
You will find the generated log in the directory specified above (C:\Temp\pdfmailer.txt).