Thank you for the hint but If I do it I get a new error
C:\Program Files\OTRS\StrawberryPerl\perl\bin>ppm Failed to load PPM_DAT file Can't use an undefined value as a SCALAR reference at C:/Program Files/OTRS/StrawberryPerl/perl/site/lib/PPM.pm line 1672, <DATA> line 41.
Furthermore there is a proxy to set with username and password; it works properly with Internet Explorer.