I want to ask if we can use the preposition by with the word Fax???
is it ok to say like fax by rima???
If so, it's correct, but I would not use passive voice here. I would simply inform the receiver of the fax that Rima sent it by filling in the information at the top right-hand side of the cover page. Sometimes the word "sender" is there to indicate where the fax came from, or who sent the fax.
Or simply signing the fax "Rima" at the end of the text works too.