You don't need an email to know someone or some bot is trying to hack your server!
You will end up with hundreds if not thousands of attempts daily, block one IP address permanently and seconds later they are back using another! This isn't just an Asterisk/FreePBX thing, the VPS this forum is hosted on has thousands of attempts daily as does every other server out there...
I have been running and maintaining servers since 2006, in all that time not once have I had a server hacked. Use long passwords that contain upper case, lower case, numbers and symbols. Set fail2ban to ban for longer periods of time, make sure your firewall is configured correctly and change your passwords regularly. You should also block direct root access and make sure your server updates remain current. If your still worried about SSH brute force attempts then use ssh keys, don't allow password logins.
I promise you, your wasting your time blocking an IP permanently. Take a look at this: https://rimuhosting.com/knowledgebase/l ... sh-attacks
Still want to block an IP address or range? take a look at this: http://www.cyberciti.biz/faq/how-do-i-b ... ux-server/