JFetcher is a Java Fetchmail application, which is able to fetch emails from a pop3 or imap mailbox and deliver it to another smtp host. The ideal exercise for JFetcher is to fetch emails from a global mailbox for relaying them to local accounts.
...see Homepage -- SpamCruncher is a small Perl-Script, that uses the SpamAssassin-engine to identify spam on remote POP3- or IMAP-Servers. So you only need SpamCruncher if your E-Mail host doesn't offer you free anti-spam services.