That depends on the type of computer you are using. There are too many answers to list here. There are two options for getting Forth files via EMail. First, you can use an EMail interface to an FTP server. Details on how to use each of those follow.
Email is the most resource intensive way to get files.
If you have access to other methods, please use those instead. If you need help determining how to construct an Internet relative EMail address, please consult your system administrator.