When sending a TIFF file as a fax attachment, the TIFF file compression must be CCITT(Group3 1d).
The properties of the TIFF image must be as follows:
File type: Tagged Information File format (TIFF)
Width: 1728 (pixels)
Height: greater then 500 (pixels)
Horizontal resolution: 204 DPI
Vertical resolution: 98 or 196 DPI (normal and fine resolution respectively)
Bit depth: 1
Color representation: monochrome (bi-level)
Compression: TIFF raw G3 Modified Huffman
To check the image properties, right click on the file, select Properties, click on the Summary Tab and press the Advanced button.