spamc 3.4.5~pre1-3 (amd64 binary) in ubuntu impish

 spamc is the client to communicate with spamd, the daemonized form of
 SpamAssassin (see the spamassassin package). It is written in C for
 maximum speed and minimum loading overhead.
 .
 spamc is quite useful for integrating spamassassin into an MTA or
 into a .procmailrc file because of its speed.
 .
 This package is useless unless you have spamassassin installed,
 either on this machine or another local machine (i.e. a mail server).