Plugin allow admin to add notice for customer to blacklist them. Once on edit order page if admin adds blacklist notice, plugin will display notice to all past and future order of that customer.
Adds Whitelist and Blacklist options for Trackbacks and Pingbacks
Prevent people from registering with emails that contain a subdomain to help reduce spam.
Remotely add known terms to the WordPress Comment Blacklist to manage spam.
Dead-Letter.Email for Wordpress. Dead simple disposable email check that just works.
Ban visitors from certain sites from viewing or adding comments.
Protect your WordPress site from unwanted registrations and spam with custom blacklist and whitelist rules.
Blacklist IP Addresses from visiting your WordPress website and Usernames from spamming. View details of all failed login attempts.
Prevent User Registration Spam, and Track New User IP address
Limit Attempts Booster is a Wordpress plugin which provides high security and limits your Wordpress access. It also safes from Brute Force Attacks.
Limit Login Attempts for login protection. Limit rate of login attempts and block IP temporarily. It is protecting from brute force attacks..
The ability to mark specific users as spammers like on Multisite install.
Monkey Trapped Spam is a WordPress plugin that automatically places the IP address of spam comments in the local comments blacklist.
NoFollow Free removes the "nofollow" tag from your Wordpress blog's comments with a lot of custom options and provides the option to insert a "NoFollow Free" band at the top of your blog.
NoMore404 is a free WordPress plugin for redirection of 404 pages and simple firewall to block malicious hosts and URLs.
You can ban suspicious traffic from accessing your website or redirect visitors to a specific page.
Post Filter allows you to replace all bad words with good ones in all post types with simple settings and easy to use interface.
You need to ban a bad user from accessing your WordPress website or admin area by user's IP address, or country. Detailed Logs and Statistics.
CyStack Security constantly monitors your websites and servers to detect security issues and vulnerabilities.