How to disable saving fax receiving log? WorkCentre 3550.

We have WorkCentre 3550 like fax receiving server. We have trouble with fax forwarding to smb server. We have two files in the folder:
Files like:
1.XXXXXX_receivingdate.pdf
2.XXXXXX_receivingdate000.log:

(START LOG) 
model name : "WorkCentre 3550";
job type : "fax rx";
id : "Skaner";
machine id : "XXXXXX";
machine number : "NNNNNN";
file name : "XXXXXX_receivingdate000";
file type : "mmr";
file format : "pdf";
file resolution : "H203 x V98";
file number : "1";
page number : "1";
fax number : "";
fax receiving result : "OK";
(END LOG) 

How to disable this log file?
Fax Defaults: Auto Report - off