Exim is a new, somewhat experimental mail transfer agent, patterned after some of the lessons learned during the development of Smail. Exim can handle relatively high volume mail systems, caching of mail delivery, header rewriting, multiple local domains from one mail system, and control over which hosts/nets may use it as a relay. exim is available via anonymous FTP from ftp.cus.cam.ac.uk [131.111.8.6], in directory /pub/software/programs/exim/.