sendfile binary package in Ubuntu Focal amd64

 Sendfile is an asynchronous file transfer service for the Internet,
 like the sendfile facility in Bitnet: Any user A can send files to
 another user B without B being active in any way.
 .
 The existing standard file transfer (ftp) is a synchronous service:
 The user must have access to an account on the sending and on the
 receiving site, too.
 .
 Sendfile for Unix, which is an implementation of the SAFT protocol
 (Simple Asynchronous File Transfer) now offers you a true
 asynchronous file transfer service for the Internet. Virtually any
 form of file can be sent, including encrypted ones. The SAFT
 protocol will be submitted as an RFC in the near future.

Source package