Compared to the Bitnet up to now there was no asynchronous file transfer service defined in the Internet. In this case one has to know the password of the recipient's account. If A and B are not the identical person, severe questions of security arise and it is not the method of choice. The file has to be uploaded by A onto the anonymous ftp server using an ftp session. After that A has to notify B about this using e-mail informing this user about the fact that the file is ready for download now.
B can get the file now by doing another ftp transfer.
During the time the file resides on the anonymous ftp server it is open to anyone, it may be readable, writeable, changeable or erasable. Encoding procedures like uuencode or MIME are available. It is not a pleasure to use either of them, they don't support all file ownership attributes and they will enlarge the amount of data to be transferred by encoding. In addition to this most of the existing MTA s are not designed to handle large amount of data transfers. This is a program for UNIX, needs no root privileges and sends its files via mail.