That is not true, Some Windows FTP clients look at the extension to try to determine how to send files. Most do not (even in windows). They rely on the settings in the application bin/ascii or auto. And also they usually try to figure out what OS the FTP server is running and that changes the ASCII sending behavior on many of them. Bottom line is you cant depend blankly on any windows FTP client to handle ascii type sends, you need to verify and test how they behave and then only count on what you have verified.