Monitoring blacklist, get notiffied when IP blacklisted

[Fli]

Hello, for a webhosting reseller, it is important to act quickly when some hosting accounts sends SPAM or hosting a phishing site. Otherwise entire reselling account / server can be suspended.

Today datacenter blocked my whole server which is under my control. Reason was that someone sent spam from more than one IP address. They received complaints at same time from more IPs.

http://www.spamhaus.org/sbl/query/incidentname
"IPhere is listed on the Spamhaus Block List (SBL)"

So here is the idea, is there any service which checks blacklists like spamhaus and notiffy by email when some of the IPs under my control appear there?

[Fli]

There are few blacklist monitoring services:

http://www.freeblacklistmonitor.com (http://www.freeblacklistmonitor.com/) - once a day, can add subnets (every 30 minutes paid)
http://www.ipchecks.net/ - twice a day
http://mxtoolbox.com/services_servermonitoring2.aspx - one free check every 7 days :(