about the data flow

hi all,
    I spent several weeks in reading the source codes. However, I still don't know the procedure of data prcessing. 
    For example, I will send a file "myexample.tiff" to a faxer. Initially the file "myexample.tiff" is stored in my hard disk,  what is the next directory it will go?  and then where ? In short, how many directories will this "myexample.tiff" go step by step before it arrive to the fax ?
  thank you.
 regards, 
 q.s.meng