To finish installation please follow these steps:

1. Edit /usr/local/etc/mimedefang/mimedefang-filter

2. Reconfigure sendmail to use MIMEDefang, for example add this lines to
   your sendmail.mc:

   MAIL_FILTER(`mimedefang', `S=local:/var/spool/MIMEDefang/mimedefang.sock, F=T, T=C:15m;S:4m;R:4m;E:10m')dnl
   define(`confINPUT_MAIL_FILTERS', `mimedefang')dnl

   rebuild sendmail.cf and install it.

Also, you can install some anti-virus software to check your mail, for example:

   security/clamav
      Open source AV package with automatic virus definition updates
   security/f-prot
      F-Prot Antivirus for BSD Workstations
   security/vscan
      Evaluation version of a DOS/Windows/Linux file virus scanner