Answer
NetPrintQueue2FAX will, by default, send a fax in high resolution. The resolution of the outbound fax can be changed to Normal Resolution by using the following Text API command in the document:::N
or
:normal
When a fax is sent in high resolution, the resolution is 200 x 200 dpi. The normal resolution of a fax, is 200 x 100 dpi.
Note: Further information on Text API commands can be found in the GFI FAXmaker user manual