Edit .bashrc which if found under the /root partition & insert the following line anywhere in between:
echo 'SSH Root Access (Your Server Name) on:' `date` `who` | mail -s "ALERT: Root Access from
who | cut -d"(" -f2 | cut -d")" -f1`" your@email-address.com
save & close the file & that's all. Now, whenever someone successfully logs in to your server as root through SSH, an email will be automatically dispatched from the server to the mentioned mail address.
Thanks!