Here is a serial# crack for winfax 4.0.
Made by the ingenious Sir Platinum.
Seem like Delrina are getting smart.
First of all in your windows temp dir create a directory called "WINFAX.T"
i.e c:\temp\winfax.t
Copy the file DCSETUP.EXE into the winfax.t directory and then make it read
only by typing attrib +r.Then go into windows and run the setup from the
Winfax disk. You will get an error message. Dont worry about it. Put in any
serial# and you are all set. If you don't make the file read only it won't work.
After you are done, in the winfax section of WINFAX.INI put this line

    Registered=YES.

Crack must be run from the temp dir stated in your AUTOEXEC.BAT
    i.e. SET TEMP=C:\TEMP  or whatever you used
Docs by Zeth Brundle.

Thanks again to Sir Platinum