If you enable anonymous access to comments in news articles, you may unintentionally receive spam on your website.
There are two ways built into DNN News Articles to handle this, Captcha & Akismet.
Enabling Captcha for News Articles
Captcha is a challenge-response security mechanism for News Articles that prompts the user to correctly submit a piece of text in a system generated image. This is done to protect your installation against malicious users scripting the entry of comments.
The Captcha looks like the following:
You can enable it in admin options -> main options -> comment settings -> use captcha:
Enabling Akismet for News Articles
Unfortunately many malicious users may have circumvented the captcha functionality. In this case, News Articles provides support for Akismet. This is a 3rd party service that allows comments to be verified before posting.
To turn this on, you will need to signup for an account at Akismet. There are two major category of accounts. Free for personal and paid for commercial. Once you have signed up for Akismet, copy the key as you'll need it in the next section.
Once you have the key, you will need to enter it in admin options -> site options -> comments settings -> akismet key
Your site should now be protected. As a comment is made, it will query Akismet to see if it is valid.
Disabling Anonymous Comments for News Articles
The other alternative is to simply disable anonymous comments. Making users register on your site will reduce anonymous comment spam but decrease functionality for y our users.
You can disable in admin options -> site options -> comment settings -> allow anonymous comments