Login-Email Spam

Hello!
Any idiots of children try to connect to my email-server for several days.
I have 2 logs in the zip-file.

Any way to stop this ****?
I ask Google, but can find a good answer :S

I have installed a ddos-protection with a nice script and Spam-protection (Spam-assassin and MagicSpam).
I have blocked some of the IPs in the Firewall.

- Hoerli