SPAM being sent to our clubs members email address

Hi
We use FreeToastHost for our club website, www.kickstarttoastmasters.co.nz .  Our group email members@kickstarttoastmasters.co.nz has been receiving spam recently.   I don't remember this happening in the past.  Is there something I need to do to stop it?  I have blacklisted the email address which appears to be the source of the most recent one.

Thanks
Ros Lee     

seems they are spamming a lot of FTH sites, we have added the domain the the server blacklist