Adding a Spam Blacklist filter to your Sendmail config

Add the following line to you sendmail.mc file use SpamCop’s email blacklist filter on your sendmail email server:

FEATURE(`dnsbl', `bl.spamcop.net', `"Spam blocked see: http://spamcop.net/bl.shtml?"$&{client_addr}')dnl

Regenerate your sendmail config with:
m4 sendmail.mc > sendmail.cf
then restart your sendmail server with
. /etc/init.d/sendmail restart

To block individual domains:

Edit /etc/mail/access

<code>
...
exmapledomain1.com    REJECT
exampledomain2.com    REJECT
...

Convert access to access.db

<code>
makemap hash /etc/mail/access.db < /etc/mail/access
</code>