In order webmasters could get notification thru email when someone had put up spam comment on a certain post, they need to enable Disqus comment moderation in the Admin> Comment > Moderation Settings.
Also setup your commenting rules in the Admin setting like these:
In blocking spammers through their email / ip address do the following:
1. Login to Disqus
2. Click Admin and hit Comments Tab
3. Under Moderation Settings, click Blacklists / Whitelists
4. Click Add Item > Put up spammers IP / email address in the blacklists pane
5. Click save, you’re done.
Note, you have also the option to remove people from the blacklist as you wish. I hope this tips would help you fight spammers attacking your blog with Disqus Comment System.